Detecting Passive RF Components Using Radio Frequency Identification Tags

ABSTRACT

Systems and methods are provided for automatically detecting passive components in communications systems using radio frequency identification (“RFID”) tags. A coupling circuit is provided in a system between a communications network and an RFID tag. The RFID tag is associated with a passive element of a distributed antenna system (“DAS”). The coupling circuit can allow an RFID signal received from an RFID transmitter over the communications network to be transported to the RFID tag. The coupling circuit can substantially prevent mobile communication signals on the communications network from being transported to the RFID tag.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/243,454, filed Sep. 23, 2011, entitled “Intelligent PatchingSystems and Methods Using Radio Frequency Identification Tags that areInterrogated over Network Cabling and Related CommunicationsConnectors,” which is incorporated by reference herein in its entirety,and claims priority to U.S. Provisional Application Ser. No. 61/695,362filed Aug. 31, 2012 and titled “Detecting the Presence of Passive RFComponents in a Distributed Antenna System Using RFID Tags,” thecontents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to communications systems and,more particularly, to automatically detecting passive components incommunications systems.

BACKGROUND

Organizations such as businesses, government agencies, schools, etc. mayemploy dedicated communications systems (also referred to herein as“networks”) that enable computers, servers, printers, facsimilemachines, telephones, security cameras and the like to communicate witheach other, through a private network, and with remote locations via atelecommunications service provider. Such communications systems may behard-wired through, for example, the walls and/or ceilings of a buildingusing communications cables and connectors. The communications cablesmay include insulated conductors such as copper wires that are arrangedas twisted pairs of conductors. Individual communications connectors(which are also referred to herein as “connector ports” and/or as“outlets”) such as RJ-45 style modular wall jacks are mounted inoffices, conference rooms and other work areas throughout the building.The communications cables and any intervening connectors providecommunications paths from the connector ports in offices and otherrooms, hallways and common areas of the building (which are alsoreferred to herein as “work area outlets”) to network equipment (e.g.,network switches, servers, etc.) that may be located in a computer room,telecommunications closet or the like. Communications cables fromexternal telecommunication service providers may also terminate withinthe computer room or telecommunications closet.

In conductive wire-based communications systems, each information signalmay be transmitted over a pair of conductors using differentialsignaling techniques rather than over a single conductor. Differentialsignaling involves transmitting signals on each conductor of thedifferential pair at equal magnitudes and opposite phases. Aninformation signal is embedded as the voltage difference between thesignals carried on the two conductors of the pair.

The conductive wire-based communication systems that are installed inboth office buildings and data centers may use RJ-45 plugs and jacks toensure industry-wide compatibility. Pursuant to certain industrystandards (e.g., the TIA/EIA-568-B.2-1 standard approved Jun. 20, 2002by the Telecommunications Industry Association), the eight conductors inRJ-45 plug and jack connectors are aligned in a row in the connectionregion where the contacts of the plug mate with the contacts of thejack. FIG. 1 is a schematic view of the front portion of an RJ-45 jackthat illustrates the pair arrangement and positions of the eightconductors in this connection region that are specified in the type Bconfiguration of the TIA/EIA-568-B.2-1 standard. As shown in FIG. 1,under the TIA/EIA-568 type B configuration, conductors 4 and 5 comprisedifferential pair 1, conductors 1 and 2 comprise differential pair 2,conductors 3 and 6 comprise differential pair 3, and conductors 7 and 8comprise differential pair 4.

The communications cables that are connected to end devices (e.g.,network servers, memory storage devices, network switches, work areacomputers, printers, facsimile machines, telephones, etc.) incommunication systems may terminate into one or more communicationspatching systems. The communications patching systems may involveconnectivity changes over time. The connections between the end devicesand the network switches may need to be changed for a variety ofreasons, including equipment changes, adding or deleting users, officemoves, etc. A network manager may implement connectivity changes bysimply unplugging one end of a patch cord or other communication cablefrom a first connector port on one of a set of patch panels and pluggingthat end of the patch cord into a second connector port on one of thepatch panels.

The connectivity between the connector ports on the network switches andthe work area outlets may be recorded in a computer-based log. Each timepatching changes are made, this computer-based log is updated to reflectthe new patching connections. Technicians may neglect to update the logeach time a change is made, and/or may make errors in logging changes.As such, the logs may not be complete and/or accurate.

Systems and method are desirable to reduce or eliminate such loggingerrors or otherwise determine the connectivity of passive components ina network.

SUMMARY

Systems and methods are provided for automatically detecting passivecomponents in communications systems using radio frequencyidentification (“RFID”) tags.

In one aspect, a system is provided. The system includes a couplingcircuit between a communications network and an RFID tag. The RFID tagis associated with a passive element of a distributed antenna system(“DAS”). The coupling circuit can allow an RFID signal received from anRFID transmitter over the communications network to be transported tothe RFID tag. The coupling circuit can substantially prevent mobilecommunication signals on the communications network from beingtransported to the RFID tag.

In another aspect, a DAS is provided. The DAS includes a communicationsnetwork, a RFID transmitter, an RFID tag, and a coupling circuit. TheRFID transmitter is positioned in a remote antenna unit. The RFID tag isassociated with a passive element remote from a position of the RFIDtransmitter over the communications network. The coupling circuitprovides a physical coupling between the RFID tag and the communicationsnetwork.

In another aspect, a method is provided. The method involves providing acoupling circuit between a communications network and an RFID tagassociated with a passive element of a distributed antenna system. Themethod further involves transmitting an RFID signal received from anRFID transmitter to the RFID tag via the communications network and thecoupling circuit. The coupling circuit substantially prevents mobilecommunication signals on the communications network from beingcommunicated to the RFID tag. The method further involves detecting thepresence of the passive element based on a responsive signal received bythe RF transceiver from the RFID tag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a contact arrangement for aconventional eight-position communications jack as viewed from the frontopening (plug aperture) of the jack.

FIG. 2 is a simplified, schematic view of an example cross-connectcommunications system on which the radio frequency identification(“RFID”) tracking techniques according to one aspect.

FIG. 3 is a block diagram of a patching connection between two patchpanels of a communications system that illustrates how RFID controlsignals can be used to automatically track patching connectionsaccording to one aspect

FIG. 4 is a flow chart illustrating methods of automatically identifyingpatching connections according to one aspect.

FIG. 5 is a schematic diagram illustrating how coupling circuits may beused to inject RFID control signals onto and/or extract the RFID controlsignals from various conductive paths of a connector port according toone aspect.

FIG. 6 is a block diagram illustrating how baluns and matching networksmay be used to provide appropriate connections between the RFIDtransmission device and the coupling circuit of FIG. 5 according to oneaspect

FIG. 7 is a block diagram illustrating how baluns and matching networksmay be used to provide appropriate connections between the RFIDtransmission device and the coupling circuit of FIG. 5 according to oneaspect.

FIG. 8 is a schematic diagram of an example coupling circuit that may beused to implement the coupling circuit according to one aspect.

FIG. 9 is a schematic diagram of an example coupling circuit that may beused to implement the coupling circuit according to one aspect.

FIG. 10 is a schematic diagram of an example coupling circuit that maybe used to implement the coupling circuit according to one aspect.

FIG. 11 is a schematic diagram of an example coupling circuit that maybe used to implement the coupling circuit according to one aspect.

FIG. 12 is a schematic diagram of an example coupling circuit that maybe used to implement the coupling circuit according to one aspect.

FIG. 13 is a schematic block diagram of a channel that illustrates howRFID control signals may be transmitted over Ethernet cabling fortracking cabling connections and end devices in a communications networkaccording to one aspect.

FIG. 14 is a schematic perspective view of an interposer according toone aspect.

FIG. 15 is a block diagram of the components of the interposer of FIG.14.

FIG. 16 is a schematic diagram that illustrates a patch cord accordingto one aspect.

FIG. 17 is a block diagram that illustrates how the patch cord of FIG.16 may be used to automatically track a patching connection in aninter-connect communications system.

FIG. 18 is a flow chart that illustrates operations for adaptivelyadjusting the power level of an RFID interrogation signal according toone aspect.

FIG. 19 is a schematic diagram illustrating a work area outlet accordingto further aspects of the present invention.

FIG. 20 is a block diagram of a patching connection between two patchpanels of a communications system according to further aspects of thepresent invention.

FIG. 21 is a block diagram of a distributed antenna system in which RFIDdetection of passive components may be used according to one aspect.

FIG. 22 is a block diagram of a remote antenna unit configured forperforming RFID detection of passive components according to one aspect.

FIG. 23 is a block diagram of an RFID tag coupled to a passive componentvia a resonant coupling circuit according to one aspect.

FIG. 24 is a block diagram of an RFID tag coupled to a passive componentvia a directional coupler according to one aspect.

FIG. 25 is a block diagram of an RFID tag coupled to an antenna via anair coupling path according to one aspect.

FIG. 26 is a block diagram of an RFID tag that is associated withmultiple coupling circuits according to one aspect.

FIG. 27 is a schematic diagram of a series resonator circuit for aresonant coupling circuit according to one aspect.

FIG. 28 is a graph depicting characteristics of a series resonatorcircuit for a resonant coupling circuit according to one aspect.

DETAILED DESCRIPTION

Aspects and examples are disclosed for detecting passive RF componentsusing radio frequency identification (“RFID”) tags. For example,distributed antenna systems (“DAS”) can be used in confined areas todeploy wireless coverage and capacity to mobile devices. A DAS caninclude active components configured to generate, process, and/orotherwise perform one or more operations on communicated signals inaddition to communicating the signals. Non-limiting examples of activecomponents include master units, extension units, and remote antennaunits. A DAS can also include passive components configured fortransceiving or otherwise communicating signals among active components.Non-limiting examples of passive components can include coaxial cable,RF splitters, RF combiners, RF antennas, optical fiber, opticalsplitters, optical combiners, connectors, jacks, wall jacks, patchcords, and the like. The presence of passive components can beidentified through the employment of RFID tags.

In accordance with some aspects, an RFID transceiver can transmit aprobing RF signal in one or more communication media of a DAS or othertelecommunication system. A coupling circuit can be coupled to awaveguide (e.g., a coaxial cable, an optical fiber, or other type ofwaveguide) to communicate a guided wave (i.e., a signal) communicatedvia the waveguide to an RFID tag. Non-limiting examples of a couplingcircuit include resonant coupling circuits, bandpass filters, low passfilters, high pass filters, directional couplers, non-directionalcouplers, and the like. The coupling circuit can maximize an amount ofRF energy received by the RFID tag from an interrogator system or otherRFID transceiver. The coupling circuit may include a physical connectionto the DAS or other communications network and circuitry that cansubstantially prevent signals other than RFID signals and responsivesignals from passing through the coupling circuit. The coupling circuitcan thus block or reduce other signals used in the DAS at differentfrequencies than the frequency used by the RFID transceiver fortransmitting probing signals. Blocking other signals at differentfrequencies can avoid or reduce generation of intermodulation productscaused by non-linear characteristics of some RFID tags. Suchintermodulation signals can be added at a harmful level to the RFsignals communicated via the DAS, thereby causing distortion and/orblockage of signals communicated to wireless devices and other terminalequipment in a coverage area serviced by the DAS.

As used herein, the term “RFID tag” is used to refer to any item thatcan respond to an RFID signal with a responsive signal representing anidentifier for the item.

In some aspects, a DAS is provided that includes one or more passivecomponents. Each passive component can be associated with a RFID tag.The RFID tag may be integrated into the passive component or may becoupled, connected, or otherwise associated with the passive component.A reader or other RF transceiver may be integrated within or otherwiseassociated with a sub-system of the DAS that is remote from at leastsome of the passive components. The reader can transceive RFID signalsover a communications network of the DAS. The communications network mayinclude, for example, coaxial cable or another transmission medium thatcan carry RF signals and RFID signals through the DAS. For example, thereader may transmit an RFID signal that is carried by the communicationsnetwork through a coupling circuit to the RFID tag associated with apassive component. The RFID tag can respond to the RFID signal with aresponsive signal representing an identifier of the passive component.The responsive signal can be received from the coupling circuit andtransported by the communications network to the reader. The reader mayextract the identifier from the responsive signal and provide theidentifier to a controller. The passive component may not be required tobe powered for a reader to detect the presence of the passive component.Receiving identifiers of passive components of a DAS can allow a diagramto be generated that represents a location of the passive componentswithin the DAS and/or losses may be identified.

In additional or alternative aspects, the coupling circuit can includean air interface between the communications network and/or passivecomponent and the RFID tag. In some aspects, both the reader and theRFID tag may be configured to be in a fixed position within the DAS, asopposed to the reader being moveable. In other aspects, the readerincludes two or more readers in which one or more readers are moveable.

In additional or alternative aspects, methods and systems (and relatedequipment) are disclosed for automatically tracking cabling connectionsin a communications system are provided in which RFID tags are installedat the connector ports of the communications system. In order to trackcabling connections in these communications systems, one or more RFIDtransceivers may be used to transmit RFID interrogation signals over thecabling to excite the RFID tags at several of the connector ports of thecommunications system. In response to these RFID interrogation signals,the RFID tags may emit responsive RFID signals that are transmitted backto an RFID transceiver over the cabling. The responsive RFID signals mayinclude, for example, unique identifiers that identify the connectorports that are associated with each RFID tag. These identifiers may beused to identify or “track” patching connections between patch panelconnector ports and/or to track horizontal cabling connections betweenpatch panel connector ports and work area outlets.

Both the RFID interrogation signals and the responsive RFID signals(which are collectively referred to herein as “RFID control signals”)that are used to identify a cabling connection between two connectorports may be transmitted over one or more of the twisted pairs ofconductors (which may also be referred to herein as a “differentialpair” or simply a “pair”) of the communications cabling that extendsbetween the two connector ports. The RFID control signals may be coupledto and from the differential pair(s) in a variety of different ways,including capacitive coupling, inductive coupling and/or by using aresonant coupling network.

The RFID control signals may be transmitted over the conductive pathsthat carry the underlying network traffic. Various different techniquesmay be used to isolate the RFID control signals from the underlyingnetwork traffic. In some aspects, the RFID control signals may betransmitted outside the frequency band that is used to carry theunderlying network traffic in order to reduce and/or minimizeinterference between the RFID control signals and the network traffic.In other aspects, the RFID control signals may be transmitted over oneof the differential pairs that is included within the cabling as acommon mode signal (i.e., as the port of a signal transmitted betweentwo devices over the conductors of a pair that is extracted by takingthe voltage average of the signals carried on the conductors of thepair). As the differential signal is extracted from the differentialpair by taking the difference between the signals carried by the twoconductors, the common mode RFID control signal is removed by thissubtraction process, and hence theoretically does not interfere with thedifferential signal. Likewise, since the equal but opposite componentsof the differential signal cancel out during the averaging process usedto recover the common mode signal, the differential signal does not(theoretically) interfere with the common mode signal. In still furtheraspects, the RFID control signals may be transmitted over two or more ofthe twisted pairs in the cabling as so-called “phantom mode” signals. Aphantom mode signal refers to a differential signal whose positive andnegative components are each transmitted as a common mode signal on atleast one pair of conductors (and hence is transmitted over at leastfour conductors). As phantom mode signals use common mode signalingtechniques, phantom mode signals likewise do not (theoretically)interfere with differential network traffic signals that may besimultaneously transmitted over the pairs. In still other aspects, theconductive paths may be sensed, and the RFID control signal may only betransmitted during time periods when there is no underlying networktraffic. Thus, one or more of a variety of different techniques may beused according to aspects of the present invention to isolate the RFIDcontrol signals from the underlying network traffic that is carried overthe same conductors.

As the RFID control signals may be transmitted on the same conductivepaths that carry the underlying network traffic, in some aspects of thepresent invention, standard cabling and patch cords may be used, whichcan reduce the overall costs of these solutions and increase theconvenience of the solution to customers. Moreover, as RFID tags arepassive devices that draw their operating power from the RFIDinterrogation signals, the connector ports according to aspects of thepresent invention may not require a separate power source. As such, theintelligent tracking capabilities may be extended to connector portsthat do not have power connections such as most modular wall jacks inthe work areas.

The methods and systems disclosed herein may be used to track patchingconnections between two patch panel fields (i.e., in cross-connectpatching systems) and/or may be used to track horizontal cablingconnections between a patch panel field and a plurality of work areaoutlets. Additionally, in some aspects, “interposer” connectors and/orcustomized patch cords may be used that may allow tracking patch cordconnections between a plurality of patch panels and a plurality ofnetwork switches (i.e., in inter-connect patching systems) and even totrack connections all the way to end devices in the work area and/or inthe computer room.

Detailed descriptions of these aspects and examples are discussed below.These illustrative examples are given to introduce the reader to thegeneral subject matter discussed here and are not intended to limit thescope of the disclosed concepts. The following sections describe variousadditional aspects and examples with reference to the drawings in whichlike numerals indicate like elements, and directional descriptions areused to describe the illustrative examples but, like the illustrativeexamples, should not be used to limit the present invention.

FIG. 2 is a schematic view of an example cross-connect communicationssystem 10 that may be used to connect computers, printers, Internettelephones and other end devices that are located in work areas 12throughout a building to network equipment that is located, for example,in a computer room 14 of the building. The RFID tracking techniquesdiscussed herein may be used to track various cabling connections in thecommunications system 10 of FIG. 2, as will be discussed in detailbelow.

As shown in FIG. 2, an example computer 20 or other end device islocated in the work area 12 of the building. The computer 20 isconnected by a patch cord 22 to a modular wall jack 24 that is mountedin a wall plate 26 in work area 12. A communications cable 28 is routedfrom the back end of the wall jack 24 through, for example, the wallsand/or ceiling of the building, to a computer room 14. As there may behundreds or thousands of work area wall jacks 24 in an office building,a large number of cables 28 may be routed into the computer room 14.While only a single work area end device (computer 20) is shown in FIG.2 to simplify the drawing, it will be appreciated that there may bedozens, hundreds or thousands of work area end devices in acommunications system.

A first equipment rack 30 is provided in the computer room 14. Aplurality of patch panels 32 are mounted on the first equipment rack 30.Each patch panel 32 includes a plurality of connector ports 34. Eachcable 28 from the wall jacks 24 in the work area 12 is terminated ontothe back end of one of the connector ports 34 of one of the patch panels32. In FIG. 2, each connector port 34 comprises an RJ-45 jack. However,it will be appreciated that other types of connector ports may be usedsuch as, for example, RJ-11 connector ports.

A communications patching system includes one or more “patch panels”that are mounted on equipment rack(s) or in cabinet(s), and a pluralityof “patch cords” that are used to make interconnections betweendifferent pieces of equipment. As is known to those of skill in the art,a “patch cord” refers to a communications cable (e.g., a cable thatincludes four differential pairs of copper wires or a fiber optic cable)that has a connector such as, for example, an RJ-45 plug or a fiberoptic connector, on at least one end thereof. A “patch panel” refers toan inter-connection device that includes a plurality (e.g., 24 or 48) ofconnector ports. Each connector port (e.g., an RJ-45 jack or a fiberoptic adapter) on a patch panel may have a plug aperture on a front sidethereof that is configured to receive the connector of a patch cord(e.g., an RJ-45 plug), and the back end of each connector port may beconfigured to receive a communications cable or a connector of a patchcord. With respect to RJ-45 connector ports, each communications cablecan be terminated into the back end of the RJ-45 connector port byterminating the eight conductive wires of the cable into correspondinginsulation displacement contacts (“IDCs”) or other wire connectionterminals of the connector port. Consequently, each RJ-45 connector porton a patch panel acts to connect the eight conductors of the patch cordthat is plugged into the front side of the connector port with thecorresponding eight conductors of the communications cable that isterminated into the back end of the connector port. The patching systemmay optionally include a variety of additional equipment such as rackmanagers, system managers and other devices that facilitate makingand/or tracking patching connections.

In an office network, “horizontal” cables can be used to connect eachwork area outlet (which can be RJ-45 jacks) to the back end of arespective connector port (which may be RJ-45 jacks) on a first set ofpatch panels. The first end of each of these horizontal cables isterminated into the IDCs of a respective one of the work area outlets,and the second end of each of these horizontal cables is terminated intothe IDCs of a respective one of the connector ports on the patch panel.In an “inter-connect” patching system, a single set of patch cords isused to directly connect the connector ports on the first set of patchpanels to respective connector ports on network switches. In a“cross-connect” patching system, a second set of patch panels isprovided, and the first set of patch cords is used to connect theconnector ports on the first set of patch panels to respective connectorports on the second set of patch panels. The second set of single-endedpatch cords can used to connect the connector ports on the second set ofpatch panels to respective connector ports on the network switches. Inboth inter-connect and cross-connect patching systems the cascaded setof plugs, jacks and cable segments that connect a connector port on anetwork switch to a work area end device can be referred to as achannel. Thus, if RJ-45 jacks are used as the connector ports, eachchannel includes four communications paths (since each jack and cablehas four differential pairs of conductors).

A rack controller 36 may also be mounted on the first equipment rack 30.The rack controller 36 may include a central processing unit (“CPU”) 38and a display 39. The rack controller 36 may be interconnected with rackcontrollers that are provided on other patch panel equipment racks ofthe communications system (only two such rack controllers 36 are shownin the example of FIG. 2) so that the rack controllers 36 cancommunicate in a common network as if they were a single controller. TheCPU 38 of rack controller 36 may include a remote access port thatenables the CPU 38 to be accessed by a remote computer such as, forexample, a system administrator computer (not shown in FIG. 2). The rackcontroller 36 may, for example, gather data from intelligent trackingcapabilities of the patch panels 32, as will be explained herein.

The communications patching system 10 further includes a second set ofpatch panels 32′ that are mounted on a second equipment rack 30′. Eachpatch panel 32′ includes a plurality of connector ports 34′, and a rackcontroller 36 may also be mounted on the second equipment rack 30′. Afirst set of patch cords 50 is used to interconnect the connector ports34 on the patch panels 32 to respective ones of connector ports 34′ onthe patch panels 32′.

As is further shown in FIG. 2, network devices such as, for example, oneor more network switches 42 and network routers and/or servers 46 aremounted, for example, on a third equipment rack 40. Each of the switches42 may include a plurality of connector ports 44, and each networkrouter and/or server 46 may also include one or more connector ports.One or more external communications lines 52 are connected to at leastsome of the network devices 46 (either directly or through a patch panelthat is not shown in FIG. 2). A second set of single-ended patch cords70 connects the connector ports 44 on the switches 42 to respective onesof the back ends of the connector ports 34′ on the patch panels 32′. Athird set of patch cords 54 may be used to interconnect other of theconnector ports 44 on the switches 42 with the connector ports providedon the network routers/servers 46. In order to simplify FIG. 2, only twopatch cords 50, a single patch cord 70 and a single patch cord 54 areshown. The communications patching system of FIG. 2 may be used toconnect each work area computer 20 or other work area end device to thenetwork switches 42, the network switches 42 to the network routers andservers 46, and the network routers/servers 46 to externalcommunications lines 52, thereby establishing the physical connectivityrequired to give devices 20 access to both local and wide area networks.In the cross-connect patching system of FIG. 2, connectivity changes canbe made by rearranging the patch cords 50 that interconnect theconnector ports 34 on the patch panels 32 with respective of theconnector ports 34′ on the patch panels 32′. It should also be notedthat in many cases the patching connections may be between patch panelsthat are mounted on the same equipment rack or even between connectorports on the same patch panel. Thus, it will be understood that FIG. 2illustrates the work area outlets being connected to patch panels thatare on a first equipment rack and the network switches being connectedto patch panels on a second equipment rack to provide a simple, easy tounderstand example. The present invention is not limited to suchconfigurations.

As will be discussed in more detail below, the RFID signaling techniquesaccording to aspects of the present invention may be used toautomatically determine and/or confirm patching connections between thepatch panels mounted on the first equipment rack 30 and the patch panelsmounted on the second equipment rack 30′ of FIG. 2, thereby allowing anetwork administrator to automatically generate and subsequentlymaintain the computer-based log of patching connections forcommunications system 10. These RFID signaling techniques may also beused to track the horizontal cabling connections between the connectorports 32 on the first equipment rack 30 and the modular wall jacks 24.Moreover, in some aspects, interposers and/or specialized patch cordsmay be used that may allow the communications system 10 to alsoautomatically track connections between the patch panels 32′ on thesecond equipment rack 30′ and the network switches 42 on the thirdequipment rack 40 and/or between the modular wall jacks 24 and the workarea end devices 20, as will be explained in further detail below.

Herein, the term “Ethernet cable” refers to a cable that includes atleast four twisted pairs of insulated conductors, where each twistedpair is configured to carry a differential signal and is suitable foruse as a transmission medium for computer communications. The term“Ethernet cabling connection” refers to one or more Ethernet cables andany intervening connectors that define a channel between two connectors(or end devices). Thus, for example, in the cross-connect system of FIG.2, the Ethernet cabling connection between modular wall jack 24 and theconnector port on switch 42 that it is connected to include horizontalcable 28, a connector port 34 on one of the patch panels 32, one of thepatch cords 50, a connector port 34′ on one of the patch panels 32′, andone of the single-ended patch cords 70.

FIG. 3 is a block diagram illustrating a simplified communicationspatching system 100 according to certain aspects of the presentinvention. The discussion below explains how RFID control signals may betransmitted over the cabling of the communications system 100 in orderto track patch cord and/or horizontal cabling connections in the system100 according to aspects of the present invention.

Referring to FIG. 3, the communications patching system 100 includes afirst patch panel 110 that has connector ports 111, 112, 113 and asecond patch panel 120 that has connector ports 121, 122, 123. The patchpanel 110 may correspond to one of the patch panels 32 in FIG. 2, andthe patch panel 120 may correspond to one of the patch panels 32′ inFIG. 2. In order to simplify the drawing, patch panels 110, 120 aredepicted as having only three connector ports each. It will beappreciated, however, that most conventional patch panels have a largernumber of connector ports, with 24-port and 48-port patch panels beingthe most commonly used patch panels in the industry. Each of theconnector ports 111-113 and 121-123 may be an RJ-45 jack that has fourdifferential pairs of conductive paths that may be used to connect theconductors of a patch cord that is plugged into the plug aperture of thejack to the corresponding conductors of a horizontal cable that isterminated into the back end wire connection assembly of the jack.

An example patch cord 130 is depicted in FIG. 3 that connects connectorport 111 on patch panel 110 to connector port 122 on patch panel 120.The patch cord 130 may be used, for example, as one of the patch cords50 of FIG. 2. While not shown in FIG. 3, it will be appreciated that theback ends of the connector ports 111-113 on the patch panel 110 may beconnected by horizontal cables to, for example, work area outlets suchas modular wall jack 24 (see FIG. 2), and that the back ends of theconnector ports 121-123 on the patch panel 120 may be connected byone-ended patch cords to, for example, connector ports on one or morenetwork switches 42 (see FIG. 2).

As is also shown in FIG. 3, a processor 117, an RFID transceiver 118,and a multiplexer 119 may be mounted on patch panel 110. Herein, theprocessor 117, the RFID transceiver 118 and the multiplexer 119 may bereferred to generically as “RFID signaling circuitry.”

The processor 117 may be any suitable microprocessor, controller,application specific integrated circuit or the like. The processor 117may control various control signaling operations that are used toidentify cabling connections that run through the connector ports111-113 on patch panel 110. The processor 117 may be in communicationwith processor 38 of FIG. 2 or, in some aspects, the processor 38 ofFIG. 2 may carry out the operations of processor 117.

The RFID transceiver 118 may be any appropriate RFID transceiver that isconfigured to, for example, generate an RFID interrogation signal thatmay be used to excite an RFID tag. The RFID transceiver 118 may alsoreceive and/or read a responsive RFID signal that is transmitted by anRFID tag in response to an RFID interrogation signal. The RFIDtransceiver 118 may generate an RFID interrogation signal in response toa control signal from the processor 117. The RFID interrogation signalthat is generated by the RFID transceiver 118 in response to such acontrol signal may be passed to the multiplexer 119. The RFIDtransceiver 118 may also receive responsive RFID signals that are passedto the RFID transceiver 118 through the multiplexer 119. The RFIDtransceiver 118 may pass data that is embedded in any receivedresponsive RFID signals to the processor 117.

The multiplexer 119 may receive RFID interrogation signals from the RFIDtransceiver 118 and pass those RFID interrogation signals to a selectedone of a plurality of coupling circuits 114, 115, 116. The multiplexer119 may likewise receive responsive RFID signals that are extracted fromthe respective channels at the coupling circuits 114, 115, 116 and passthese signal to the RFID transceiver 118. The multiplexer 119 maycomprise, for example, an analog multiplexer that is configured to passsignals in the frequency ranges of the RFID control signals discussedherein. In some aspects, the multiplexer 119 may be replaced with aswitching circuit. Various examples of switching circuits that may beused to selectively connect an RFID transceiver to the connector portson a patch panel in place of the multiplexer 119 of FIG. 3 are describedin U.S. patent application Ser. No. 11/871,448, filed Oct. 12, 2007 andpublished as U.S. Patent Publication No. 2009/0096581, the entirecontents of which is incorporated herein by reference. In some aspects,the multiplexer 119 (or alternative switching circuit) may be omitted(e.g., by providing a separate RFID transceiver 118 for each couplingcircuit 114, 115, 116).

The coupling circuits 114, 115, 116 are provided to couple RFID controlsignals between the RFID signaling circuitry 117, 118, 119 and therespective channels that run through connector ports 111, 112, 113. Forexample, an RFID interrogation signal that is generated by RFIDtransceiver 118 may be routed by the multiplexer 119 to an outputthereof that is connected to, for example, coupling circuit 114. Theappropriate output of the multiplexer 119 is selected based on a controlsignal that is provided to the multiplexer 119 from the processor 117.The coupling circuit 114 couples the RFID interrogation signal that isreceived from the multiplexer 119 onto one of the differential pairs ofconductors of the channel that passes through connector port 111. Insome aspects, the RFID interrogation signal may be coupled as a phantommode control signal that is coupled onto two (or more) of the fourdifferential pairs of conductive paths through the connector port 111.The coupling circuits 114, 115, 116 likewise are used to extractresponsive RFID signals from the channel that are transmitted by an RFIDtag in response to an RFID interrogation signal so that these signalsmay be passed to the RFID transceiver 118 via the multiplexer 119.Example coupling circuits are discussed below with reference to FIGS.8-12.

As is further shown in FIG. 3, the second patch panel 120 includescoupling circuits 124-126 that are associated with connector ports121-123, respectively. As noted above, example coupling circuit designsare illustrated below with respect to FIGS. 8-12. The coupling circuits124-126 may be used to couple RFID interrogation signals from thechannels associated with connector ports 121-123, respectively, and passthose RFID interrogation signals to a respective RFID tag 127-129. Thecoupling circuits 124-126 likewise may be used to inject responsive RFIDsignals that are transmitted by RFID tags 127-129, respectively, ontothe channels associated with the respective connector ports 121-123.

The RFID tags 127-129 may each comprise a small integrated circuit chipthat is mounted, for example, within or adjacent to its respectiveconnector port 121-123. The RFID tags 127-129 may each have a computermemory in which data may be stored specifically including, for example,a unique identifier. The RFID tags 127-129 are designed to receive anRFID interrogation signal from the RFID transceiver 118 (or another RFIDtransceiver) which is used to energize or “excite” the RFID tag 127-129.The excited RFID tags 127-129 transmit a responsive signal that mayinclude the data (e.g., the unique identifier) that is stored in thememory of the RFID tag 127-129. The RFID tags 127-129 may not require aseparate power source, as they may be designed to use the energy fromthe received RFID interrogation signal to transmit the responsive RFIDsignal. As will be discussed in greater detail herein, the RFID tags127-129 may differ from many conventional RFID tags in that they may bedesigned to be energized via a hard-wired (as opposed to wireless)connection, and as they may transmit their responsive signal over thehard-wired connection.

FIG. 4 is a flow chart illustrating operations according to aspects ofthe present invention that may be used to identify a cabling connectionbetween the first connector port 111 on patch panel 110 (the “localjack”) and the second connector port 122 (the “remote jack”) on patchpanel 120 of the communications system 100 of FIG. of FIG. 3.

Referring to FIGS. 3 and 4, operations may begin with the RFIDtransceiver 118 transmitting an RFID interrogation signal to the firstconnector port 111 (block 140). This RFID interrogation signal may betransmitted, for example, in response to a control signal that istransmitted to the RFID transceiver 118 by the processor 117. In aspectsthat share the RFID transceiver 118 amongst multiple connector ports(such as the aspect of FIG. 3), the multiplexer 119 or anotherappropriate switching circuit may be used to route the RFIDinterrogation signal to the appropriate connector port 111. Themultiplexer 119 may be controlled, for example, by control signals thatare received from the processor 117.

In some aspects, the RFID interrogation signal may be transmitted at afrequency that is outside the frequency band used to transmit theregular network traffic that is carried by the communication system. Forexample, Ethernet signals according to the IEEE 802.3 series aretransmitted at frequencies between 0.15 and 800 MHz with a 3 dB roll-offat approximately 400 MHz for a 10 Gigabit/second Ethernet signal (“theEthernet spectrum”). The upper and lower frequency limits of theEthernet spectrum are subject to change as the relevant standardsevolve. In order to reduce possible interference between the RFIDinterrogation signal and the underlying network traffic that is carriedas differential signals on the channels of the communications system,the RFID interrogation signals may be transmitted, for example, atfrequencies below 0.15 MHz (e.g., at about 140 kHz) or at frequenciesabove 400 MHz (e.g., at frequencies of about 800 MHz). However, atfrequencies below 0.15 MHz, the supportable data rate for the RFIDcontrol signals may be low, and mode conversion and/or attenuation mayincrease substantially at frequencies above 400 MHz. Thus, it will beappreciated that, in other aspects, the RFID interrogation signal may betransmitted as common mode or phantom mode signals at frequencies thatare within the Ethernet spectrum, and the inherent isolation betweencommon mode/phantom mode signals and underlying differential informationsignals (or other appropriate isolation techniques) may be relied uponfor keeping interference between the RFID interrogation signal and theunderlying information signals at acceptable levels. In still furtheraspects, the RFID interrogation signal may be transmitted within theEthernet spectrum, but only during time periods where there is nounderlying network traffic on the channel.

The RFID interrogation signal that is received at the connector port 111is next coupled onto the channel that runs through connector port 111(block 145). Coupling circuit 114 in FIG. 3 is used to couple the RFIDinterrogation signal onto this channel. As will be discussed in greaterdetail herein with respect to FIGS. 8-12, resonant coupling circuits,capacitive coupling circuits and/or inductive coupling circuits may beused in some aspects to couple the RFID interrogation signal onto thechannel.

The coupling circuit 114 may couple or “inject” the RFID interrogationsignal onto one or more of the eight conductive paths that run throughconnector port 111 (which, as noted above, are configured as fourdifferential pairs of conductive paths). In some aspects, the RFIDinterrogation signal may be injected as a common mode signal onto, forexample, one of the differential pairs of conductive paths. In otheraspects, the RFID interrogation signal may be injected as a phantom modesignal that has a first component that is transmitted over a first ofthe differential pairs of conductive paths as a common mode signal and asecond component—that has a polarity that is opposite the firstcomponent—that is transmitted as a common mode signal over a second ofthe differential pairs of conductive paths. As noted above, for a signalsuch as an RFID interrogation signal is transmitted on one or moredifferential pairs of conductors using common mode or phantom modesignaling techniques, the common mode/phantom mode signal theoreticallyshould not interfere with any underlying differential informationsignals that are being transmitted over the differential pair(s). Instill other aspects, the RFID interrogation signal may be transmitted ata frequency that is outside the frequency range of the regular networktraffic that is carried by the communication system 100 and/or duringtime periods when no network traffic is present on the channel.Accordingly, in each of the above—described aspects, the RFIDinterrogation signal may be transmitted over a channel simultaneouslywith any data signals that are transmitted over the channel.

Once the RFID interrogation signal is injected into the channel at thefirst connector port 111, it will be transmitted over the patch cord 130to the second connector port 122 (block 150). The RFID interrogationsignal is extracted from the channel at the second connector port 122using the coupling circuit 125 which, in turn, provides the RFIDinterrogation signal to the RFID tag 128 (block 155). The couplingcircuit 125 may be implemented, for example, using any of the circuitsdescribed herein that may be used to implement coupling circuit 114.

The RFID interrogation signal is designed to excite the RFID tag 128. Asdescribed above, an excited RFID tag 128 can be configured to emit aresponsive RFID signal. This responsive RFID signal may includeinformation that is stored in a memory of the RFID tag 128. In someaspects, the memory of the RFID tag 128 may include a unique identifierthat identifies the second connector port 122. The memory may alsoinclude other information such as, for example, location information forthe second connector port 122. Thus, in response to the RFIDinterrogation signal, the RFID tag 128 transmits a responsive RFIDsignal that includes the unique identifier from the memory of the RFIDtag 128 to the second connector port 122 (block 160).

The responsive RFID signal may be coupled onto one or more of the fourdifferential pairs of conductive paths of the second connector port 122(block 165). In some aspects, the responsive RFID signal may be coupledas a common mode signal onto, for example, one of the differential pairsof conductive paths. In other aspects, the responsive RFID signal may becoupled as a phantom mode signal onto two of the differential pairs ofconductive paths. In still other aspects, the responsive RFID signal maybe coupled as a differential signal onto one of the differential pairsof conductive paths, where the frequency of the responsive RFID signalis outside the frequency range of the regular network traffic that iscarried by the communication system 100 (i.e., outside the Ethernetspectrum) and/or during time periods when no regular network traffic ispresent on the channel. In each of these cases, the responsive RFIDsignal should not substantially interfere with any underlyingdifferential information signals that are being transmitted over thechannel.

Once the responsive RFID signal is injected onto the conductive paths ofthe second connector port 122, it passes to the corresponding conductivepaths of the first connector port 111 over the conductors of the patchcord 130 (block 170). The responsive RFID signal is can be extractedfrom the channel at the first connector port 111 by the coupling circuit114 and provided to the RFID transceiver 118 via the multiplexer 119(block 175).

In some cases, multiple responsive RFID signals may be received at theRFID transceiver 118 from the channel that runs between the firstconnector port 111 and the second connector port 122 (block 180). Thismay occur, for example, because a responsive RFID signal from anotherchannel may couple into the channel at issue (e.g., by coupling from onepatch cord to an adjacent patch cord for multiple patch cords arebundled together). If multiple responsive RFID signals are received, theRFID transceiver 118 may select the responsive RFID signal that has thelargest received signal strength as being the signal that was forwardedfrom the second connector port 122 (block 185), as signals that arecapacitively or inductively coupled though, for example, the cablingshould have significantly lower received signal strengths. Next, theunique identifier in the responsive RFID signal (or of the selectedresponsive RFID signal, if multiple responsive RFID signals arereceived) is used to identify the patch cord connection betweenconnector ports 111 and 122, and this connection may be logged in aconnectivity database (block 190). Operations for identifying thepatching connection between the first connector port 111 and the secondconnector port 122 may be completed.

A number of approaches have been proposed for using RFID tags to trackcabling connections in communications systems. Examples of suchapproaches are disclosed in U.S. Pat. Nos. 6,002,331, 7,170,393 and7,605,707. The other proposed approaches may embed an RFID tag in eachplug of the patch cords of a communications system (where the RFID tagson each end of a given patch cord include the same identifier). One ormore RFID transceivers are mounted on each patch panel, and various RFIDantenna arrangements have been proposed which may be used to wirelesslytransmit RFID interrogation signals to the RFID tags in any plugs thatare connected to the patch panel and to receive responsive RFID signalsthat are transmitted by these RFID tags and forward the received signalsto the RFID transceiver. By sending out a series interrogation signals,these systems can identify the specific patch cord plug that is insertedinto each connector port on the patch panel. If such tracking is done ateach patch panel in the communications system, the patch cordconnections between the various patch panel connector ports may beidentified.

In contrast to these previously proposed approaches, aspects of thepresent invention associate each RFID tag with a specific connector portas opposed to with a patch cord plug. As a result, the need forspecialized patch cords that have RFID tags embedded therein may beeliminated in various of the aspects disclosed herein. Moreover, as theRFID tags are located at the connector ports as opposed to in the patchcord plugs, the communications systems according to aspects of thepresent invention may track cabling connections through horizontalcabling connections (which may not include plugs), thereby allowingtracking of connections into the work areas. Additionally, as the RFIDcontrol signals are transmitted using the cabling as a transmissionmedia as opposed to the air interface used in prior approaches, thepossibility of false positives that may occur in the prior approacheswhen an RFID antenna associated with a first connector port excites anRFID tag on a plug that is inserted within an adjacent connector portmay be reduced or eliminated. Moreover, the use of the cabling as atransmission medium for the RFID control signals allows using RFIDtransceivers that are located at one location (e.g., within a computerroom) to interrogate RFID tags that are located at remote locations(e.g., at work area outlets or even at work area end devices).

As noted above, aspects of the present invention may use couplingcircuits such as circuits 114-116 and 124-126 of FIG. 3 to couple theRFID control signals to and from a channel. FIGS. 5-12 provideadditional details regarding the operation of example coupling circuits.For example, FIG. 5 is a schematic diagram illustrating how the couplingcircuits according to aspects of the present invention may be used toinject and/or extract RFID control channels onto various conductivepaths of a connector port. FIGS. 6-7 are block diagrams that illustratehow baluns and/or matching networks may be used to provide appropriateconnections between RFID transmission devices (e.g., an RFID transceiveror an RFID tag) and the coupling circuits according to aspects of thepresent invention. Finally, FIGS. 8-12 illustrate several examplecoupling circuits that may be used to implement the coupling circuits114-116 and 124-126 of FIG. 3.

Turning first to FIG. 5, this figure provides additional details as tohow a coupling circuit 200 may be used to couple RFID control signalsfrom an RFID transmission device 195 (e.g., an RFID transceiver or anRFID tag) to and from one or more of the differential pairs of aconductive paths that run through a connector port 220. As shown in FIG.5, the connector port 220 includes a total of eight conductive paths221-228 that are arranged as four differential pairs of conductive paths231-234. These eight conductive paths 221-228 are electrically connectedto respective ones of eight conductors of a communications cable 240that is terminated into the back end of the connector port 220, and tothe respective eight plug blades of a plug 245 that is inserted into theplug aperture of the connector port 220. The plug 245 is part of a patchcord 248 that extends between the connector port 220 and a connectorport on another device (e.g., on another patch panel or on a networkswitch).

The RFID transmission device 195 may be configured to transmit andreceive either single-ended or differential RFID control signals. Ifconfigured to transmit/receive single-ended RFID control signals, theRFID transmission device 195 will include a single output port 196,while if configured to transmit/receive differential RFID controlsignals, the RFID transmission device 195 will include a pair of outputports 196, 197. The coupling circuit 200 may have a single input port201 (if the RFID transmission device 195 is a single-ended device) or apair of input ports 201, 202 (if the RFID transmission device 195outputs differential RFID control signals).

The coupling circuit 200 further includes a pair of output ports 203,204. If the coupling circuit 200 is designed to operate on single-endedRFID control signals, the coupling circuit 200 is configured to pass asingle-ended control signal that is received at input port 201 to bothof the output ports 203, 204. If the coupling circuit 200 is designed tooperate on differential RFID control signals, the coupling circuit 200is configured to pass the first component of a differential RFID controlsignal (or some portion thereof) that is received at input port 201 tothe output port 203, and to pass the second component of thedifferential RFID control signal (or some portion thereof) that isreceived at input port 202 to the output port 204. As shown in FIG. 5,the output ports 203, 204 of the coupling circuit 200 are coupled to therespective conductive paths 221, 222 of the first differential pair ofconductive paths 231 that carry a differential signal through theconnector port 220. Thus, as shown in FIG. 5, if the RFID transmissiondevice outputs a single-ended RFID control signal, the coupling circuit200 may be used to inject this RFID control signal as a common modesignal onto the conductive paths 221, 222 of the first differential pairof conductive paths 231 of connector port 220. If instead, the RFIDtransmission device outputs a differential RFID control signal, thecoupling circuit 200 may be used to inject this differential RFIDcontrol signal as a differential signal onto the conductive paths 221,222 of the first differential pair of conductive paths 231 of connectorport 220. For cases where such differential RFID control signals areused, the differential RFID control signal can be transmitted at afrequency that falls outside of the frequency range of the underlyingnetwork traffic that may be carried on the first differential pair ofconductive paths 231 and/or during time periods when no network trafficis present on the channel in order to avoid interference between theRFID control signal and the network traffic. Moreover, while operationof the coupling circuit is described above with respect to RFID controlsignals that are transmitted from the RFID transmission device 195 tothe connector port 220, it will be appreciated that the coupling circuit200 may be a bi-directional coupling circuit that likewise may be usedto extract RFID control signals from the first differential pairs ofconductive paths 231 and pass these RFID control signals to the RFIDtransmission device 195.

As is further shown in FIG. 5, in other aspects the coupling circuit 200may also include a second pair of output ports 205, 206. This additionalpair of output ports 205, 206 may be included if the coupling circuit isdesigned to operate on phantom mode signals. For example, if the RFIDtransmission device 195 outputs a differential RFID control signal, thefirst component of that signal (i.e., the component input to thecoupling circuit at input port 201), or a portion thereof, may be passedby the coupling circuit 200 to output ports 203, 204 where it isinjected as a common mode signal onto the conductive paths 221, 222 ofthe first differential pair of conductive paths 231 of connector port220. Likewise, the second component of the differential RFID controlsignal (i.e., the component input to the coupling circuit at input port202), or a portion thereof, may be passed by the coupling circuit 200 tooutput ports 205, 206 where it is injected as a common mode signal ontothe conductive paths 223, 224 of the second differential pair ofconductive paths 232 of connector port 220. As the differential RFIDcontrol signal is injected onto the differential pairs of conductivepaths 231,232 as two common mode signals, the frequency of the RFIDcontrol signal may be within the frequency range of the underlyingnetwork traffic.

Most RFID transceivers are single-ended devices that output single-endedRFID interrogation signals, and that receive single-ended RFID controlsignals. As discussed above with respect to FIG. 5, the coupling circuit200 may be designed to inject such single-ended RFID control signals ascommon mode signals onto one of the differential pairs of conductivepaths of connector port 220. However, in order to reduce the impact ofexternal noise sources on the RFID control signals that are used inaspects of the present invention, it may be desirable to usedifferential RFID control signals that are less susceptible tocorruption from external noise sources. FIG. 6A illustrates an examplecircuit that may be used to convert a single-ended RFID control signalinto a differential signal, and vice versa. For example, as shown inFIG. 6, the single-ended output of an RFID transceiver 195 may be inputto a balun 210. As known to those of skill in the art, baluns may beused to convert a single-ended signals into differential signals andvice versa. Baluns or other appropriate circuits may also be provided ateach connector port to convert single-ended responsive RFID signals thatmay be emitted by the RFID tags into differential responsive RFIDsignals, if desired. However, it may be preferable to instead implementthe communications system using RFID tags that emit differentialresponsive RFID signals, in order to avoid the increased costs that maybe associated with providing baluns or other suitable conversioncircuits at each connector port in the communication system.

As will be discussed below with respect to FIGS. 8-12, in some aspectsof the present invention, the coupling circuit 200 may directly connectRFID transmission device 195 (e.g., an RFID transceiver or an RFID tag)to a channel. In such aspects, this direct connection should besufficiently matched in order to ensure that the RFID control signalsare properly terminated. For example, if a device is connected at theend of the channel running through connector port 220 of FIG. 5 (e.g., acomputer or other Ethernet device is coupled to the far end of patchcord 248), then any RFID control signal that is coupled onto the channelby coupling circuit 200 will experience a load of 100 ohms, as Ethernetdevices are designed to have 100 ohm terminations to match the 100 ohmcabling. If, instead, no device is connected at the far end of thechannel (i.e., the far end of patch cord 248 is not plugged into adevice), then the RFID control signal will experience an open circuit.The coupling circuit 200 may be designed to exhibit a load ofapproximately 100 ohms so that if no device is connected at the end ofthe channel, the coupling circuit 200 will terminate the RFID controlsignal to a load of approximately 100 ohms. If a device is connected,the RFID control signal will be terminated with two 100 ohm terminationsthat are in parallel, which leads to a relatively small degree ofmismatch for the RFID control signals. In cases where the RFID controlsignal is coupled into connector port 220 using phantom modetransmission techniques, the impedance could deviate from the 100 ohmimpedance of the twisted pair transport media. The line matching needsto accommodate the specific matching to the cables impedance. Inaddition, the phantom mode control signals are expected to experience atermination that may be close to an open circuit, as the phantom modeshould not be terminated by a regular RJ-45 connector nor by an enddevice different to a RFID tag or RFID transceiver.

It will also be appreciated that the RFID tags that are used in aspectsof the present invention may or may not be designed to have anappropriate output impedance such as a 100 ohm impedance. Thus, asillustrated in FIG. 7, in some aspects a matching network 215 may beprovided between each RFID tag 195 and its respective coupling circuit200 in order to properly match the RFID tag to the coupling circuit soas to achieve acceptable return loss performance. In some aspects, asingle-ended 50 ohm to differential 100 ohm balun may be used as thebalun 210 of FIG. 6 in order to perform impedance matching. However, itwill be appreciated that the balun 210 could have different impedancevalues.

As noted above, the coupling circuit 200 may couple the RFID controlsignals to and from the channel in a variety of different ways,including via resonant coupling, capacitive coupling and/or inductivecoupling. FIGS. 8-12 illustrate example designs that may be used toimplement the coupling circuit 200.

FIGS. 8-10 illustrate three example resonant coupling circuits. Each ofthese coupling circuits may be used to directly connect RFIDtransmission device 195 to one or more of the differential pairs ofconductive paths 231-234 of connector port 220, as the resonant couplingcircuit acts as a filter that only passes signals within a specifiedfrequency range. One advantage of using resonant coupling techniquesthat allow for such a direct connection is that the coupling may involveonly a relatively small attenuation of the RFID control signal. Incontrast, for capacitive and/or inductive coupling techniques being used(as is discussed below with reference to FIGS. 11 and 12), the RFIDcontrol signal may be attenuated by 10 dB (or much more) each time it iscoupled to or from the channel, as capacitive/inductive coupling maypass far less energy than a direct (resonant) electrical connection. Foran RFID control signal that is coupled both to and from the channel,attenuations of two times the coupling loss plus two times the path losson the channel may occur with a total loss that can exceed 20 dB (e.g.,an attenuation of up to 100 dB might be anticipated) for capacitive andor inductive coupling circuits being used. With resonant couplingcircuits, signal attenuation may be substantially less (such as, forexample, 1 dB). Resonant coupling may allow for the use of reducedamplitude RFID control signals which may be less likely to interferewith differential Ethernet information signals that are beingtransmitted over the channel.

FIG. 8 illustrates a differential low pass coupling circuit 300 that maybe used to pass, for example, signals that are in a frequency range thatis below a certain cut-off frequency while blocking signals that areabove this frequency. The differential low pass coupling circuit 300 maybe used, for example, when the RFID control signals are transmitted atfrequencies below 0.15 MHz. Appropriate inductor and capacitor valuesmay be selected to set the cut-off frequency at an appropriate level. Itwill be appreciated that FIG. 8 illustrates one representativedifferential low pass coupling circuit design, and that any appropriatelow pass filter circuit could be used.

FIG. 9 illustrates a differential high pass coupling circuit 310 thatmay be used to pass, for example, signals that are in a frequency rangethat is above a certain cut-off frequency while blocking signals thatare below this frequency. The differential high pass coupling circuit310 may be used, for example, when the RFID control signals aretransmitted at frequencies above 400 MHz. Appropriate inductor andcapacitor values may be selected to set the cut-off frequency at anappropriate level. It will be appreciated that FIG. 9 illustrates onerepresentative differential high pass coupling circuit design, and thatany appropriate high pass filter circuit could be used.

FIG. 10 illustrates a differential band pass coupling circuit 320 thatmay be used to pass, for example, signals that are within a specifiedfrequency range, while blocking signals that are at frequencies eitherabove or below the specified range. The differential band pass couplingcircuit 320 can be used in place of the differential high pass couplingcircuit 310. The differential band pass circuit 320 may provide improvedperformance over the differential high pass coupling circuit 310 as itallows less signal energy into the channel by filtering out, forexample, high frequency harmonics. Appropriate inductor and capacitorvalues may be selected to set the upper and lower cut-off frequencies ofthe differential band pass coupling circuit at appropriate levels topass the RFID control signals. It will be appreciated that FIG. 10illustrates one representative differential band pass coupling circuitdesign, and that any appropriate band pass filter circuit could be used.

FIG. 11 illustrates an alternative example coupling circuit 360 that maybe used to implement the coupling circuits 114-116 and 124-126 of FIG.3. For example, FIG. 11 is a simplified and enlarged perspective view ofa portion of a connector port 350 such as connector ports 111-113 and121-123 of FIG. 3 that includes the coupling circuit 360. The couplingcircuit 360 uses capacitive coupling to couple RFID control signals toand from two of the differential pairs of conductive paths that runthrough the connector port 350. The description below describes how thecoupling circuit 360 may be used to couple differential RFID controlsignals to and from a channel of the connector port 350. Additionaldetails regarding the design of the connector port 350 will be omittedhere since such a description is provided in U.S. patent applicationSer. No. 13/110,994, filed May 19, 2011, the entire content of which isincorporated herein by reference. The coupling circuit 360 is designedto inject (or extract) a phantom mode RFID control signal onto two ofthe differential pairs of conductive paths of the connector port 350.

As shown in FIG. 11, the connector port 350 includes eight springcontacts 351-358 which are configured to make physical and electricalcontact with the blades of a mating plug which is received within theplug aperture (not shown) of the connector port 350. The contacts351-358 are referred to as “spring” contacts because they are configuredto resiliently deflect from a resting position when contacted by amating plug, then spring back to the resting position when the plug isremoved. As discussed above with respect to FIG. 1, these springcontacts 351-358 may be arranged as four differential pairs of contacts,with contacts 354-355 comprising the first differential pair, contacts351-352 comprising the second differential pair, contacts 353, 356comprising the third differential pair, and contacts 357-358 comprisingthe fourth differential pair. Each spring contact 351-358 may have atermination end (not shown) that terminates in a printed circuit board359, and a distal end which resides above the printed circuit board 359.The free ends of the spring contacts 351-358 terminate near the forwardedge of printed circuit board 359, and may be offset vertically from thetop surface of printed circuit board 359 when the spring contacts351-358 are in their normal resting position (i.e., in the position thatthey assume when not engaged by a mating plug). Each spring contact351-358 is part of a respective one of eight conductive paths that areused to connect the eight conductors in a cable that is terminated intothe back end of the connector port 350 to respective ones of the eightconductors of the patch cord that is plugged into the plug aperture ofthe connector port 350.

As shown in FIG. 11, a plurality of contact pads 361-364 are provided onthe top surface of the printed circuit board 359. When the modular plugis inserted into plug aperture of the connector port 350, the distalends of each of the spring contacts 351-352, 357-358 are deflecteddownwardly so as to come into mechanical and electrical contact with arespective one of the contact pads 361-364. The contact pads 361-364 areused to capacitively couple RFID control signals to and from pairs 2 and4 of the connector port 350 (as discussed with respect to FIG. 1 above,pairs 2 and 4 are the outside pairs of contacts in the TIA/EIA 568 typeB contact configuration), as will be discussed in further detail below.

As is further shown in FIG. 11, first and second plates 370, 380 areembedded in interior layers of the printed circuit board 359. The firstplate 370 is positioned under the contact pads 361-362 that electricallyconnect to the conductors of pair 2, and the second plate 380 ispositioned under the contact pads 363-364 that electrically connect tothe conductors of pair 4. Plate 370 is electrically connected by aprinted circuit board trace 372 to a conductive post 374, and plate 380is electrically connected by a printed circuit board trace 382 to aconductive post 384. The conductive posts 374, 384 are electricallyconnected to respective first and second outputs of a differential RFIDtransmission device 195 (see FIG. 5).

The plate 370 and the contact pads 361 and 262 are separated by a layerof the printed circuit board 359. These components together form a pairof capacitors that may be used to capacitively couple a portion of an IDcontrol signal to and/or from the respective first and second conductorsof one of the four differential pairs of conductive paths that runthrough the connector port 350. For example, the plate 370 and thecontact pad 361 form a first capacitor that is disposed between the RFIDtransmission device 195 (see FIG. 5) and the first conductive paththrough the connector port 350, and the plate 370 and the contact pad362 together form a second capacitor that is disposed between the RFIDtransmission device 195 and the second conductive path through theconnector port 350.

The plate 380 and the contact pads 363 and 364 are also separated by alayer of the printed circuit board 359. These components together formanother pair of capacitors that may be used to capacitively couple aportion of a differential RFID control signal to and/or from therespective first and second conductors of a second of the differentialpairs of conductive paths that run through the connector port 350. Theplate 380 and the contact pad 363 can form a third capacitor that isdisposed between the RFID transmission device the contact pad 364together form a fourth capacitor that is disposed between the RFIDtransmission device 195 and the eighth conductive path through theconnector port 350. Thus, the first pair of capacitors formed byelements 370, 361, 362 and the second pair of capacitors formed byelements 380, 363, 364, along with their corresponding electricalconnections (e.g., traces 372, 382 and posts 374, 384) together form thecapacitive coupling circuit 360 that may be used to couple differentialRFID control signals between the RFID transmission device 195 anddifferential pairs 2 and 4 of the connector port 350. In the aspect ofFIG. 11, the RFID control signals are coupled onto the channel asphantom mode signals, although it will be appreciated that in otheraspects (not pictured), the coupling circuit could instead be designed,for example, to couple the RFID control signal onto a singledifferential pair of the channel as a common mode signal or as anout-of-band differential signal.

A differential RFID control signal may be coupled as a phantom modesignal onto the conductive paths of pairs 2 and 4 of connector port 350from the RFID transmission device 195 as follows. A first component ofthe RFID control signal (e.g., the positive component) is passed fromthe RFID transmission device 195 to the conductive plate 370, and thesecond component of the RFID control signal (e.g., the negativecomponent) is passed from the RFID transmission device 195 to theconductive plate 380. A portion of the first component of the RFIDcontrol signal is capacitively coupled from the conductive plate 370through the dielectric substrate of printed circuit board 359 to thecontact pads 361 and 362, and a portion of the second component of theRFID control signal is capacitively coupled from the conductive plate380 through the dielectric substrate of printed circuit board 359 to thecontact pads 363 and 364. When a plug is received within the plugaperture (not shown) of the connector port 350, the plug blades pressthe spring contacts 351-358 downwardly so that the distal ends of springcontacts 351, 352, 357, 358 make firm mechanical and electrical contactwith their respective mating contact pads 361-364. When this occurs, thefirst component of the differential RFID control signal passes from thecontact pad 361 to spring contact 351 and from the contact pad 362 tospring contact 352, thereby injecting the first component of thedifferential RFID control signal onto the conductive paths of pair 2 asa common mode signal. Likewise, the second component of the differentialRFID control signal passes from the contact pad 363 to spring contact357 and from the contact pad 364 to spring contact 358, therebyinjecting the second component of the differential RFID control signalonto the conductive paths of pair 4 as a common mode control signal(e.g., a magnitude that is reduced by 70 dB) is transferred from plate370 to the spring contacts of pair 2, and a reduced magnitude version ofthe second component of the RFID control signal (e.g., a magnitude thatis reduced by 70 dB) is transferred from plate 380 to the springcontacts of pair 4.

The coupling circuit 360 may likewise be used to extract phantom modeRFID control signals from pairs 2 and 4 of the conductive paths ofconnector port 350 and pass the extracted RFID control signal to theRFID transmission device 195. As the process is identical except thatthe direction of transmission of the RFID control signals is reversed,description of this reverse coupling process will be omitted. FIG. 12 isa block diagram of another alternative coupling circuit 390 that may beused to implement the coupling circuit 114-116 and 124-126 of FIG. 3.The coupling circuit 390 uses inductive coupling to couple differentialRFID control signals to and from two of the differential pairs ofconductive paths that run through a connector port (only two of thepairs of conductive paths of the connector port are shown in FIG. 12).

As shown in FIG. 12, a pair of center tapped inductors 392, 394 areprovided. The two ends of the first of these inductors 392 are connectedto the respective first and second conductive paths of a first of thedifferential pairs of conductive paths (pair 2) running through theconnector port (the connector port is not shown in FIG. 12), and the twoends of the second of these inductors 394 are connected to therespective first and second conductive paths of a second of thedifferential pairs of conductive paths (pair 4) running through theconnector port. A first component of the differential RFID controlsignal (i.e., the positive component) may be coupled to the first centertapped inductor 392, and a second component of the differential RFIDcontrol signal (i.e., the negative component) may be coupled to thesecond center tapped inductor 394. The first center tapped inductor 392inductively couples the first component of the differential RFID controlsignal onto each conductive paths of pair 2, and the second centertapped inductor 394 inductively couples the second component of thedifferential RFID control signal onto each conductive path of pair 4. Aswith the circuits of FIG. 11, the differential RFID control signal iscoupled onto the differential pairs of the connector port as a phantommode signal that will generally not interfere with any differentialsignals that are carried on pairs 2 and 4. A similar inductive couplingcircuit for coupling a phantom mode control signal onto two differentialpairs of conductors is disclosed in U.S. Pat. No. 7,573,254 to Cobb etal., the entire contents of which is incorporated herein in itsentirety.

FIG. 13 is a schematic block diagram that illustrates a channel 400 thatruns between a first connector port 412 on a network switch 410 and aconnector port 452 on a work area end device 450. In the particularexample shown, this channel 400 extends through one patch panelconnector port 422 on a first patch panel 420, a patch panel connectorport 432 on a second patch panel 430 and a modular wall jack 440. Itwill be appreciated, however, that any number of connector ports may beincluded between the network switch connector port 412 and the enddevice connector port 452. For example, the channel 400 couldadditionally include one or more additional patch panel connector portsand or one or more consolidation point connector ports. Note that tosimplify the drawings, only a single connector port is illustrated onthe network switch 410 and the patch panels 420, 430.

As shown in FIG. 13, the patch panel 420 includes a processor 429, anRFID transceiver 428 and a multiplexer 426. Operations may begin withthe processor 429 sending a control signal to the RFID transceiver 428.In response to the control signal, the RFID transceiver 428 may generateand transmit an RFID interrogation signal that is passed to themultiplexer 426. The processor 429 also sends a control signal to themultiplexer 426 that controls the multiplexer 426 to route the RFIDinterrogation signal to a coupling circuit 424 that is associated with aselected connector port (port 422) on patch panel 420. Example couplingcircuit designs are discussed above with respect to FIGS. 8-12. Thecoupling circuit 424 couples the RFID interrogation signal onto at leastsome of the conductive paths of the connector port 422.

The RFID interrogation signal that is injected onto the conductive pathsof connector port 422 passes to the conductors of a patch cord 421 thatextends between connector port 422 on patch panel 420 and connector port432 on patch panel 430. As shown in FIG. 13, the connector port 432 onpatch panel 430 has an associated coupling circuit 434 and an associatedRFID tag 436 (as will every other connector port on patch panel 430).The RFID tag 436 has a memory that may include, for example, a uniqueidentifier and location information for its associated connector port432. In some aspects, the unique identifier could be the serial numberor MAC ID of the first patch panel 430 combined with a port number thatidentifies the connector port 432. A portion of the RFID interrogationsignal is coupled from the connector port 432 by the coupling circuit434 and passed to the RFID tag 436.

The portion of the RFID interrogation signal that is passed to the RFIDtag 436 energizes the RFID tag 436. When energized, the RFID tag 436emits a responsive Attorney Docket No. 9833-7 RFID signal that includes,for example, some or all of the information stored in the RFID tagmemory, specifically including the unique identifier. The differentialresponsive RFID signal is passed to the coupling circuit 434 where it isinjected onto one or more of the differential pairs of connector port432. The responsive RFID signal is then passed over the patch cord 421back to connector port 422 of patch panel 420. At the connector port422, the responsive RFID signal is passed from the one or moredifferential pairs of connector port 422 to the coupling circuit 424,where it is passed to the RFID transceiver 428 via the multiplexer 426.The RFID transceiver 428 receives the responsive RFID signal andextracts the unique identifier and any other data that is included inthe responsive RFID signal. This unique identifier is passed to theprocessor 429, thereby notifying the processor 429 that a patchingconnection exists between connector port 422 and connector port 432. Theprocessor 429 may provide this information to, for example, a rackmanager (e.g., rack manager 36 of FIG. 2), a system manager (not shown)and/or other processing devices that create and/or maintain a log of thepatch cord and cabling connections in the communications patchingsystem.

Once the RFID interrogation signal is injected into the channel 400 thatruns through the connector port 422, the RFID interrogation signal willpass along the entire length of the channel 400. Consequently, the RFIDinterrogation signal will also pass through the patch panel connectorport 432 and over the horizontal cable 431 to the wall jack 440, andwill then pass over the patch cord 441 to the interposer 454 that ismounted on the end device connector port 452. Likewise, the RFIDinterrogation signal will pass in the other direction over the patchcord 411 that connects patch panel connector port 422 to the interposer414 mounted in the switch connector port 412. The interposers 414 and454 are special connectors that each converts a standard connector portinto a connector port that works in conjunction with one of the couplingcircuits according to aspects of the present invention. The design andoperation of an example interposer is discussed below with reference toFIGS. 14-15.

Focusing first on the RFID interrogation signal that travels overhorizontal cable 431, this signal will enter the wall jack 440 where aportion of it is coupled from the channel by the coupling circuit 442.The coupling circuit 442 is electrically connected to an RFID tag 444that has memory that may include, for example, a unique identifier andlocation information for the wall jack 440. The portion of the RFIDinterrogation signal that is passed to the RFID tag 444 energizes theRFID tag 444 so that it emits a responsive RFID signal that includes,for example, some or all of the information stored in the RFID tagmemory, specifically including the unique identifier. The responsiveRFID signal is passed back to the coupling circuit 442 where it isinjected onto one or more of the differential pairs of conductive pathsrunning through the wall jack 440. The responsive RFID signal will passover the horizontal cable 431 and the patch cord 421 back to theconnector port 422 on patch panel 420. At the connector port 422, theresponsive RFID signal is passed from the differential pair(s) ofconductive paths of connector port 422 to the coupling circuit 424,where it is passed to the RFID transceiver 428 via the multiplexer 426.The RFID transceiver 428 receives the responsive RFID signal andextracts the unique identifier for wall jack 440 therefrom. This uniqueidentifier is passed to the processor 429, thereby notifying theprocessor 429 that connector port 422 is also connected to the wall jack440. The processor 429 may provide this information to, for example, arack manager (e.g., rack manager 36 of FIG. 2), a system manager (notshown) and/or other processing devices that create and/or maintain a logof the patch cord and cabling connections in the communications patchingsystem.

The RFID interrogation signal will also travel over patch cord 441 tothe interposer 454 that is inserted into the end device connector port452, and will likewise travel from connector port 422 on patch panel 420over the cable 411 to the interposer 414 that is inserted into theswitch connector port 412. The RFID interrogation signal will be coupledfrom the coupling circuits 456 and 416 to the RFID tags 458 and 418,respectively, which will in turn each generate a responsive RFID signalthat is injected back into the channel and received by the RFIDtransceiver 428. The manner in which the interposers 414 and 454 may beused to inject and extract RFID control signals to and from a channelwill be described in detail below with reference to FIGS. 14-15.

Note that in the above-described aspect, a single RFID interrogationsignal can energize multiple RFID tags at approximately the same time(e.g., RFID tags 436, 444, 418 and 458 in the example of FIG. 13). Ifmultiple RFID tags are transmitting at the same time, the transmittedsignals may interfere with each other, making it difficult or impossibleto read the unique identifier associated with each RFID tag.Accordingly, arbitration techniques may be used to cause the RFID tagsthat are on any given channel to sequentially transmit to avoid suchinterference.

In some aspects, the above-described arbitration capability may beprovided by using specialized RFID tags that support an arbitrationprocedure. The arbitration procedure can, for example, provide a methodensuring that only one RFID tag that is coupled to a particular channeltransmits information at a time and/or provide a way of obtaining theunique identification codes even when multiple RFID tags transmitinformation simultaneously. In some aspects, RFID tags may be used thatare designed to automatically perform an arbitration procedure whenmultiple RFID tags are excited at the same time by an RFID transceiver.If such RFID tags are used, the RFID transceiver may issue a commandthat takes the RFID tags out of transponder talk first mode. The RFIDtransceiver then issues a command that causes each RFID tag to transmitits unique identification code at a well-defined rate, such that eachRFID tag transmits each bit of its identification code at the same timethat the other RFID tags are transmitting the corresponding bit of theiridentification codes. At some point, the identification bits beingtransmitted by the multiple RFID tags will not all match. This will berecognized by the RFID transceiver as a “collision,” and the RFIDtransceiver will then transmit an instruction telling only the RFID tagsthat were transmitting, for example, a “1” when the collision occurredto continue sending the remainder of their identification bits. Eachtime a subsequent collision occurs, the RFID transceiver transmitsanother instruction that commands only the RFID tags that weretransmitting, for example, a “1” to continue transmitting. This processcontinues until only a single RFID tag is transmitting and that tag hastransmitted its full unique identification code. The RFID transceiverthen returns to a previous branch point (i.e., a point where aninstruction was transmitted) and takes a different path (i.e., if theprevious instruction commanded only the RFID tags transmitting a “1” tocontinue transmitting, then the “different path” may be an instructioncommanding only the RFID tags transmitting a “0” to continuetransmitting) to obtain another unique identification code. This processcontinues until the RFID transceiver has a complete list of the uniqueidentification codes of each excited RFID tag. It will be appreciatedthat various other techniques may be used to address the potentialproblem of multiple RFID tags transmitting responsive signals at thesame time such as, for example, assigning each RFID tag a particulartime slot in a time division multiple access communication scheme or theuse of a frequency division multiple access scheme. Other procedures andtechniques may also be used.

Thus, as described above with respect to FIG. 13, pursuant to aspects ofthe present invention, RFID control signals may be passed along networkcabling in order to identify all of the patching connections on eachchannel in a communications system.

It may also be desirable to automatically track the identity of the enddevices that are coupled to a particular channel. By way of example, ifthe end devices are automatically tracked, then it may be possible tohave security measures in place that automatically disable networkswitch connector ports when an unauthorized device is connected to achannel. As another example, when end devices are automatically tracked,the communications system can be designed to automatically reconfigurevirtual local area networks upon sensing the connection of an authorizedend device in order to provision pre-defined services to thenewly-connected end device.

End devices that can be connected to communications systems of the typedescribed herein are manufactured by a large number of manufacturers.These manufacturers may not agree to include coupling circuits on theconnector ports of these end devices that could be used to inject andextract RFID control signals from the channel and to further includeRFID tags for their devices. As such, the connector ports on most if notall end devices may not allow discovery of information regarding the enddevice. To address this potential shortcoming, interposer communicationsconnectors are provided that may be used on network switches and/or workarea end devices to facilitate automatically tracking patchingconnections and/or automatically identifying end devices according tocertain aspects of the present invention.

FIGS. 14-15 illustrate an example interposer 500 according to certainaspects of the present invention. For example, FIG. 14 is a schematicperspective view of an interposer 500, and FIG. 15 is a schematic blockdiagram that illustrates the functional components of the interposer500.

Referring first to FIG. 14, it can be seen that the interposer 500 is acombination plug-jack connector that includes a plug end 502 that has aplug housing and eight plug blades, and a jack end 504 that isterminated with a communications jack (e.g., an RJ-45 jack). The plugend 502 of the interposer 500 may be plugged into a connector port(e.g., an RJ-45 jack) on an end device such as a network switch or awork area computer. The jack end 504 of the interposer 500 may be nearlyidentical to a conventional RJ-45 jack, except that instead of havingwire connection terminals (e.g., IDCs) as output ports, the jack insteadincludes printed circuit board traces for each conductive path thatconnect to respective ones of the plug blades on the plug end 502 of theinterposer 500. The plug end 502 of interposer 500 may be plugged into aconnector port of an end device, and the jack end 504 of the interposer500 may receive the plug on the patch cord that connects to the enddevice. As such, the interposer 500 can be inserted in series into thechannel at the location of the end device.

Turning to FIG. 15, it can be seen that the interposer 500 additionallyincludes an embedded or associated coupling circuit 506 such as, forexample, any of the coupling circuits described above with reference toFIGS. 7A-E, as well as an RFID tag 508 that is electrically connected tothe coupling circuit 506. The coupling circuit 506 may be used toextract RFID interrogation signals from the channel and pass those RFIDinterrogation signals to the RFID tag 508. The RFID tag 508 may have amemory that stores a unique identifier (e.g., a MAC ID) for the enddevice. The coupling circuit 506 may likewise inject a responsive RFIDsignal that is transmitted by the RFID tag 508 onto the channel. Thecommunications system may excite the RFID tags in the interposers 500that are mounted on, for example, work area end devices or networkswitches in the same manner discussed above that the system can excitethe RFID tags on remote patch panel connector polis and wall jacks inorder to identify the end devices that are connected to each channel inthe communications system. Thus, when interposers such as interposer 500are used, the system manager can track end-to-end connectivityinformation for each channel.

Moreover, to prevent a particular interposer 500 from being removed fromone end device and placed on another end device (which may result inmisidentification of the end device), the plug portion of eachinterposer 500 may include a locking mechanism that a networkadministrator may use to lock the interposer 500 into a connector porton an end device. This locking mechanism may be designed such that it isdifficult (or impossible) for someone without an unlocking key to removethe interposer 500 from an end device without damaging the interposer500 and rendering it inoperable. For example, a locking mechanism suchas the locking mechanism disclosed in U.S. Patent ApplicationPublication No. 2010/0136809 may be used.

The interposer 500 preferably should be nearly invisible electrically sothat the inclusion of the interposer 500 does not appear as anotherconnection in the channel. This may be accomplished, for example, bydesigning different interposers 500 for use with different end devices,where the interposer 500 is specifically tuned to provide a high degreeof crosstalk cancellation and low return losses when used in theconnector port on the end device at issue.

Pursuant to still further aspects of the present invention, customizedpatch cords may be used instead of interposers to track patchingconnections to end devices that have standardized connector ports thatdo not include the coupling circuits or RFID tags that are used inaspects of the present invention. These customized patch cords may beused, for example, to track patching connections in inter-connectcommunications systems. FIG. 16 is a schematic diagram that illustratesone example design for such a customized patch cord. FIG. 17 is a blockdiagram that illustrates how the use of such customized patch cords mayallow for automatically tracking patching connections in aninter-connect communications system without the use of interposers.

As shown in FIG. 16, the patch cord 550 includes a first plug 552, asecond plug 554 and a cable 560 extending there between. The first plug552 may be a standard RJ-45 communications plug, and the cable 560 maybe a standard cable for an RJ-45 patch cord. The second plug 554 mayalso be identical to a standard RJ-45 communications plug, except thatthe second plug 554 further includes a coupling circuit 556 according toaspects of the present invention (e.g., any of the coupling circuitsdescribed above with reference to FIGS. 7A-7E) and an antenna 558 thatis connected to the coupling circuit 556. Operation of this specializedpatch cord will now be described with reference to the block diagram ofFIG. 17.

As shown in FIG. 17, the patch cord 550 may be used in an inter-connectpatching system to connect a first connector port 111 on a patch panel110 to a connector port 572 on a network switch 570. The patch panel 110is already described above with reference to FIG. 3, and hence furtherdescription thereof will be omitted. The network switch 570 may be aconventional network switch that includes a plurality of connector ports571-573. Additionally, labels 574, 577, 580 are mounted (e.g.,adhesively) adjacent to the respective connector ports 571-573 on thenetwork switch 570. As shown in FIG. 17, each label 574, 577, 580includes a respective RFID tag 575, 578, 581 and a respective RFIDantenna 576, 579, 582. Each RFID tag 575, 578, 581 includes a uniqueidentifier stored in a memory thereof that identifies the respectiveconnector port 571-573 that the RFID tag 575, 578, 581 is associatedwith. Each RFID antenna 576, 579, 582 is connected to a respective oneof the RFID tags 575,578, 581. The customized patch cords 550 (only oneof which is shown in FIG. 17) and the labels 574, 577, 580 may be usedto automatically track patching connections between patch panel 110 andnetwork switch 570 as follows.

The RFID transceiver 118 on patch panel 110 transmits an RFIDinterrogation signal over the patch cord 550 in the exact same mannerthat an RFID interrogation signal is transmitted over patch cord 130 inthe communications system of FIG. 3. However, in the inter-connectcommunications system of FIG. 17, the network switch 570 does notinclude a specialized connector port that has an associated couplingcircuit to extract the RFID interrogation signal from the channel.Accordingly, in the inter-connect communications system of FIG. 17, theRFID interrogation signal is wirelessly transmitted using the antenna558 on patch cord 550 to the RFID tags that are, for example, adhesivelyapplied adjacent to each connector port 571-573 on the network switch570 in order to allow automatic identification of the patchingconnections to the network switch 570.

For example, when the RFID interrogation signal reaches the second plug554, a portion thereof is extracted from the channel by the couplingcircuit 556, which feeds this RFID interrogation signal to the antenna558. The antenna 558 transmits this RFID interrogation signal wirelesslyto the RFID antenna 579 on the label 577 that is associated withconnector port 572. The RFID antenna 579 passes this RFID interrogationsignal to its associated RFID tag 578. The RFID tag 578 is excited bythe received RFID interrogation signal and, in turn, emits a responsiveRFID signal that includes a unique identifier that is stored in thememory tag 578. This responsive RFID signal is passed to the RFIDantenna 579, which transmits the responsive RFID signal to the antenna558 on patch cord 550. The responsive RFID signal is passed by thecoupling circuit 556 onto the channel of patch cord 550, where it canthen pass to the RFID transceiver 118 on patch panel 110 in the samemanner described above with respect to FIG. 3 that responsive RFIDsignals are passed through patch cord 130 to RFID transceiver 118.

The antenna 558 and/or the RFID antennas 576, 579, 582 may be designedso that the signals that they transmit are transmitted directionallyand/or for a very short distance, in order to ensure that only a singleresponsive RFID signal will be received by the antenna 558 in responseto an RFID interrogation signal that is transmitted by antenna 558.Suitable RFID antenna designs that will achieve this are disclosed, forexample, in the above-referenced U.S. patent application Ser. No.11/871,448.

As noted above, signal attenuation increases with increasing frequency.Accordingly, when RFID control signals are used that are at frequenciesabove the Ethernet spectrum, signal attenuation may raise challenges,particularly in communications systems that have long cabling runs(e.g., cabling runs exceeding 100 meters) or communications systems thatreactively (as opposed to resonantly) couple the RFID control signals toand from the channels of the communications system. Accordingly, in someaspects, the RFID control signals can inject higher magnitude RFIDcontrol signals, specifically including signals having magnitudes thatexceed the magnitudes permitted for Ethernet signals under theabove-referenced Category 5, 5E, 6 and 6 a standards. These highermagnitude RFID control signals may be used because significant isolationmay be provided between the RFID control signals and the underlyingnetwork traffic by frequency separation, time separation and/or by useof common mode or phantom mode signaling techniques.

Pursuant to further aspects of the present invention, the transmit powerused for the RFID interrogation signals may be adjusted in order toreduce or minimize parasitic responses from RFID tags that are onchannels other than the channel on which an RFID interrogation signalwas transmitted. Such parasitic responses may arise because of unwantedcoupling between channels that can occur when connector ports arelocated in very close proximity (which can be the case with patchpanels, network switches, and some multi-socket modular wall jacks)and/or when patch cords or horizontal communications cables are bundledtogether. In some aspects, the power level of the RFID interrogationsignals may be set to be sufficiently high such that the RFIDinterrogation signal can energize each RFID tag on its channel, and sothat the responsive RFID signals from the RFID tags have sufficientmagnitude to be detected by the RFID transceiver, yet preferably not beso high that the RFID interrogation signal gives rise to parasiticresponsive RFID signals and/or interferes too much with underlyingnetwork traffic.

In some aspects, the magnitude of the RFID interrogation signals may beadaptively adjusted. In some aspects, the RFID transceiver may transmita series of RFID interrogation signals having increasing magnitudesuntil a responsive RFID signal is received from an RFID tag associatedwith a particular connector port along the channel. The specificmethodology used to adaptively adjust the power level of the RFIDinterrogation signal may depend on the configuration of the system(e.g., a different methodology may be used depending upon the number ofRFID tags that may potentially be provided on a given channel). Forpurposes of illustration, the flow chart of FIG. 18 illustratesoperations for adaptively adjusting the power level of an RFIDinterrogation signal that is used to track patching connections betweenpatch panel ports (e.g., patching connections in a cross-connectpatching system) according to certain aspects of the present invention.

As shown in FIG. 18, operations may begin with an RFID transceiversetting a transmit power for an RFID interrogation signal that is to betransmitted over a first channel at a first level (block 520). Then theRFID transceiver transmits an RFID interrogation signal at this powerlevel over the channel (block 525). The RFID transceiver next determineswhether or not a responsive RFID signal is received at the RFIDtransceiver from an RFID tag (block 530). If no responsive RFID signalis received within a predetermined time period, then a determination ismade as to whether or not a maximum transmit power has been reached(block 535). If so, operations end. If the maximum transmit power hasnot been reached, then the RFID transceiver may increase the outputpower of the transmitter (block 540). Operations then return to block525 where the RFID transceiver sends another RFID interrogation signal.Once at block 530 it is determined that a responsive RFID signal wasreceived at the RFID transceiver from an RFID tag, then the power levelof the RFID interrogation signal may be stored (block 545), andoperations may end. This stored power level may then be used insubsequent operations (or, alternatively, a slightly higher power levelto provide some margin). In this fashion, the RFID transceiver mayensure that sufficiently strong RFID interrogations signals are usedwhile at the same time reducing the risk of parasitic responses and/orthe impact of the RFID interrogation signals on the underlying Ethernettraffic by taking steps to cap the magnitude of the RFID interrogationsignals once a sufficient signal magnitude is achieved.

Pursuant to further aspects of the present invention, RFID interrogationsystems are provided that may make use of new variations of the Ethernetstandard that define energy efficient Ethernet (IEEE 802.3az). In thisnew flavor of the IEEE 802.3 standard, the Ethernet transmitters areturned off when no data needs to be send, which will reduce theinterference. In systems that transmit according to the IEEE 802.3azstandard, the RFID transceivers according to aspects of the presentinvention may transmit control signals in the gaps between the regularnetwork traffic, and hence may transmit at lower power levels and avoidinterfering with the regular network traffic. Moreover, the RFID controlsignals could be transmitted using the spectrum that the regular networktraffic usually occupies.

FIG. 20 is a block diagram of a patching connection between two patchpanels that illustrates yet another aspect of the present invention. Asis readily apparent, the block diagram of FIG. 20 is identical to theblock diagram of FIG. 3, except that the block diagram of FIG. 20further includes Ethernet channel activity sensors 111′, 112′, and 113′that are provided on patch panel 110 to monitor whether or not regularnetwork traffic is present on the channels that run through connectorports 111, 112, and 113, respectively. In the aspect illustrated in FIG.20, the RFID transceiver 118 may monitor the activity on the channelsrunning through connector ports 111, 112, and 113 and only transmit RFIDcontrol signals when no regular network traffic is sensed as beingpresent on the channel that the RFID control signal is to be transmittedover. This technique avoids interference between the regular networktraffic and the RFID control signals, and hence the RFID control signalsmay be transmitted at frequencies that are within the Ethernet spectrum.When an active Ethernet end device is connected to one of the channels,the RFID interrogation procedure will have already discovered most ofthe channel configuration. Thus, the RFID interrogation system may sensethe newly added active Ethernet end device in the first moment when thedevice is connected to the Ethernet channel before Ethernetcommunications are established with the end device. In other words, theRFID detection may Attorney Docket No. 9833-7 be designed to occur veryquickly after the physical connection is established, but before theEthernet channel is actively transmitting. The last detected RFID tagmay be kept in the database and may be considered valid because anychange to the physical connection may disrupt the Ethernet channel,which disruption may be sensed by the Ethernet channel activity sensors111′, 112′, and 113′ and used to trigger additional RFID interrogation.In this aspect, the RFID spectrum and the Ethernet spectrum couldpotentially be overlapping, as the Ethernet channel activity sensors111′, 112′, and 113′ may be used to avoid practical interference betweenthe RFID interrogation systems and the regular network traffic. In suchaspects, the RFID transceiver 118 could be configured to only performRFID interrogations during time periods when there is no regular networktraffic on the channel at issue.

Returning again to FIG. 18, it will be understood that theabove-described operations that are illustrated in FIG. 18 may becarried out periodically for each channel in a communications system,and the system may store data regarding how the power level of the RFIDinterrogation signal that is necessary to receive a response from eachRFID tag in the communications system changes over time. This data couldperiodically be analyzed to identify channels that require higher powerlevels over time, which may be an indication of degraded performance oncabling and/or connectors along the channel or increased interferencefrom external noise sources (e.g., computer equipment, other cables,etc.). System administrators could then perform more detailed testing onchannels that exhibit such degraded performance to determine the causesthereof.

As explained above, each RFID tag may be read from a remote location(e.g., from each patch panel). Additionally, the RFID tags may also beaccessed locally. By way of example, a portable interrogation device mayhave a patch cord attached thereto that may be plugged into work areaconnector ports. The portable device may include an RFID transceiverthat transmits an RFID interrogation signal onto the patch cord. TheRFID interrogation signal is passed from the patch cord onto the channelin the manner described above where it excites the RFID tag in the workarea connector port. The RFID tag generates a responsive RFID signalthat is injected into the channel and then extracted from the channel atthe connector port of the portable device (which may be a connector portaccording to aspects of the present invention).

In some aspects, such a portable interrogation device may also be usedto program information into the RFID tags (e.g., at the remote connectorports) when a communications system is first installed. For example, theportable device may be connected to a tablet personal computer or otherprocessing device. The tablet personal computer may be used to programinformation into the memory of the RFID tag such as, for example,location information specifying the location of the connector port atissue. Thus, once the connector ports in a building are installed, atechnician can use the above-referenced portable device and tabletcomputer to program location information into each RFID tag.

Pursuant to still further aspects of the present invention, work areaoutlets may optionally include an RFID antenna that is connected inparallel to the RFID tag. This RFID antenna may be used to wirelesslyread information from, or write information to, the RFID tag. Hence, byproviding the RFID antenna, a technician may wirelessly read informationfrom, or program information into, each RFID tag, thereby avoiding theneed to plug a patch cord of a portable device into each work areaoutlet. FIG. 19 is a schematic diagram illustrating a work area outlet600 that includes such an RFID antenna. As shown in FIG. 19, theconnector port 600 includes four differential pairs of conductors601-604 that are part of the channel that runs through the connectorport 600. A coupling circuit 610 is provided that may be used to injectand/or extract control signals to and/or from one or more of thedifferential pairs of conductors 601-604. The coupling circuit 610 iscoupled to an RFID tag 620. An RFID antenna 630 is also provided. TheRFID antenna 630 and the coupling circuit 610 are hard-wired in parallelto the RFID tag 620.

When connector ports are provided that have the design of work areaoutlet 600, portable devices (not shown) may be used that include anRFID transceiver and an antenna to wirelessly excite the RFID tag 620that is associated with outlet 600. For example, the RFID transceiver ofthe portable device may transmit an RFID interrogation signal through anantenna of the portable device. This RFID interrogation signal may bereceived by the RFID antenna 630 that is hard-wired to the RFID tag 620,and the received RFID interrogation signal may be used to excite theRFID tag 620. Once excited, the RFID tag 620 generates a responsive RFIDsignal that is transmitted by the RFID antenna 630. This responsive RFIDsignal may be received by the antenna on the portable device and passedto the RFID transceiver thereof.

The portable device may likewise be used to place the RFID tag into aprogram mode in order to download information (e.g., a uniqueidentifier, location information, etc.) into the memory of the RFID tag.By providing a wireless link it may be possible for technicians to morequickly program information into the memories of the RFID tags 620mounted on the work area outlets 600.

In some aspects, each of the connector ports in the communicationssystem may also include a plug insertion/removal detection circuit.Suitable circuits for detecting plug insertions and removals are knownin the art including, for example, the circuits disclosed in U.S. patentapplication Ser. Nos. 12/787,486, 13/111,112 and 13/111,015, and in U.S.Pat. No. 6,424,710. The provision of these plug insertion/removaldetection circuits allows the intelligent tracking system to operate asan event-driven system. For example, instead of performing periodicscans to determine all patching connections in a communications network,the system can monitor for plug insertions and/or removals and onlytransmit RFID interrogation signals after the detection of such pluginsertions and removals to update the connectivity information. In someaspects, connectivity information could be tracked and updated usingboth event driven signaling and periodic scans that may be performed ona less frequent basis.

As discussed above, RFID tags may be provided for each connector port inthe communications system. In some aspects, the RFID tags may be mountedin or on a housing of the connector port. In other aspects, the RFIDtags may be mounted on an associated mounting structure such as a faceplate for a modular wall jack or a mounting frame of a patch panel. Insome aspects, the RFID tag may be mounted directly on a printed circuitboard that includes some or all of the conductive paths of the connectorport. Thus, it will be appreciated that the RFID tag may be mounted inany appropriate location.

In some aspects, the RFID control signals may be used to monitor forchanges in the transmission line characteristics of the patch cordsand/or horizontal cabling in a communications system. This is possiblebecause the characteristics of the responsive RFID signals are known,and hence if changes in the transmission line such as increasedtemperature occur, this can be detected via detected changes in thecharacteristics of the received responsive RFID control signals.

Pursuant to still further aspects of the present invention, the RFIDtags that are embedded in the connector ports of a communications systemmay be used to combat counterfeiting. In recent years, counterfeiting ofconnector ports, patch cords and horizontal cables has increasedsignificantly. This counterfeiting may involve a third partymanufacturer directly copying another manufacturer's products,specifically including the other manufacturers external look and feel,color scheme, product names, product numbers and the like so that thecounterfeit product is indistinguishable from the genuine product whenviewed by an end user. In some cases, the counterfeiter also directlycopies the internal characteristics of the genuine product, while inother cases the counterfeiter uses different internal designs thatalmost always exhibit inferior performance. Such counterfeiting AttorneyDocket No. 9833-7 inevitably damages a manufacturer in the form of lostsales, and may also cause significant reputational damages (whichresults in additional lost sales) when the counterfeit products performmore poorly than the genuine products. The unique identifiers that arestored in the memory of the RFID tags according to aspects of thepresent invention may be used to combat counterfeiting as follows.

The unique identifiers can be stored in the RFID tags using a secret keyencryption algorithm. The provider of the connector ports may maintain alist of the unique identifiers. Once a system is installed, the uniqueidentifiers for all of the RFID tags may be collected by a systemmanager. This list may be provided to the manufacturer of the connectorports, who can then compare the list to production records to determinewhether or not all of the unique identifiers match the unique identifierof a connector port that was manufactured by the manufacturer. Themanufacturer may also keep track of where each connector port isinstalled, and thus if the same unique identifier is submitted multipletimes the manufacturer will be able to identify that counterfeiting isincurring. The manufacturer can, for example, require that the list ofunique identifiers be provided as a condition for issuance of a warrantycertificate. The above techniques may be particularly effective inidentifying distributors who purchase counterfeit products and mix themin with legitimate products.

As noted above, in addition to a unique identifier, other usefulinformation may be programmed into the memory of each RFID tag. Suchinformation may include location information that identifies thelocation of the connector port on which the RFID tag is mounted. In someaspects, this location information may be a floor number, a room numberand a socket number. In other aspects, it may be the GPS coordinates ofthe connector port location (perhaps with a floor number as well, as GPSgenerally will not provide such information). Additional informationsuch as, for example, a picture of the room and outlet, a drawing of theoutlet position, date of manufacture information, etc. may also bestored in the memory of the RFID tag. This information may be stored ina write-protected mode and/or as encrypted information. This allows thesystem manager to read this information directly from each RFID tag,thereby eliminating the need to manually enter and/or import suchinformation into the system manager.

According to still further aspects of the present invention, multipleRFID tags may be included in some or all of the work area outlets, whereeach RFID tag is designed to emit responsive RFID signals that are atdifferent frequencies. For example, a first of the RFID tags maytransmit responsive RFID signals at 150 kHz, and the second of the RFIDtags may transmit responsive RFID signals at 433 MHz. The provision ofmultiple RFID tags per connector port may be used, for example, tomonitor the frequency characteristics of the horizontal cables that areattached to the respective work area outlets. For example, low qualityEthernet cables tend to exhibit lower margins (or even negative margins)at higher frequencies. By measuring the signal-to-noise ratio of theresponsive RFID signals that are received from the multiple RFID tags,it may be determined if lower quality cable is connected to specificconnector ports. Additionally, if the attenuation is known as a functionof temperature and frequency, the frequency-dependent attenuation of theresponsive RFID signals that may be measured based on the responsiveRFID signals received from the multiple RFID tags.

Aspects of the present invention may have a number of distinctadvantages over prior intelligent patching approaches. For example, someaspects of the present invention may use conventional communicationscables and patch cords that do not include extra conductors,identification chips, special contacts and the like. The inclusion ofsuch extra elements as required by various prior art intelligentpatching approaches can increase the cost of the cabling infrastructure,can prevent use of the already installed cabling and patch cord base,may increase the size, weight and cost of the cabling and has variousother potential disadvantages. Some aspects of the present inventionalso may require only minimal changes to the connector ports in acommunications system such as, for example, the provision of capacitorsthat are used to transfer the RFID control signals to and from theconnectors and the provision of an RFID tag that may be implemented atrelatively low cost. Moreover, the RFID protocol is well established andvery robust, and hence has the potential to provide a highly reliableintelligent tracking system.

Moreover, while the provision of the RFID transceiver, processor andmultiplexer may increase the cost of the systems according to aspects ofthe present invention, only a few of these components may be required asthey may be shared across all of the channels that run through a patchpanel, and hence the overall impact on the cost of the system may bemanageable. Moreover, the intelligent tracking capabilities of thecommunications systems according to aspects of the present invention mayextend to the work area in order to track patch cord and cablingconnections to consolidation points and wall jacks, and interposers orother techniques may be used to perform tracking all the way to enddevices in both the work area and the computer room to provide fullend-to-end tracking. Such tracking of end devices may also enable a hostof other capabilities such as, for example, automatic enablement ofswitch ports upon detection of the connection of an authorized device,the automatic deployment of services in response to detection of theconnection of an authorized device, etc. Such capabilities may, forexample, simplify network operation, result in power savings (byallowing unused switch ports to be set to a non-enabled state).

In additional or alternative embodiments, DAS can be used in confinedareas to deploy wireless coverage and capacity to mobile devices. A DAScan include active components such as (but not limited to) master units,extension units, and remote antenna units. A DAS can also includepassive components. Non-limiting examples of such passive components caninclude coaxial cables, RF splitters, RF combiners, RF antennas, opticalfiber, optical splitters, optical combiners, connectors, jacks, walljacks, patch cords, and the like.

For example, FIG. 21 is a block diagram depicting a DAS 1400. The DAS1400 can include a master unit 1402 as a donor device and remote antennaunits 1404 a-c.

The DAS 1400 can communicate with one or more base stations via a wiredor wireless communication medium. The master unit 1402 can communicateuplink and downlink signals between the base stations and one or moreremote antenna units 1404 a-c distributed in the environment to providecoverage within a service area of the DAS 1400. The master unit 1402 canconvert downlink signals received from the base stations, such as RFsignals, into one or more digital data streams for transmission to theremote antenna units 1404 a-c. The remote antenna units 1404 a-c canconvert digital data streams to RF signals. The remote antenna units1404 a-c can amplify the downlink signals and radiate the downlinksignals to terminal equipment such as mobile communication devices.

A system controller 1406 can control the operation of the master unit 22for processing the signals communicated with the remote antenna units1404 a-c. The signals communicated with the remote antenna units 1404a-c may be the uplink and downlink signals of the DAS 1400 forcommunicating with terminal equipment.

The master unit 1402 can provide downlink signals to the remote antennaunits 1404 a-c via the links 1405 a-c. The links 1405 a-c can includeany communication medium suitable for communicating data via digitizedsignals between the master unit 1402 and the remote antenna units 1404a-c. The digitized signals may be communicated electrically oroptically. Non-limiting examples of a suitable communication medium forthe links 1405 a-c can include copper wire (such as a coaxial cable),optical fiber, and microwave or optical communication link.

Although the DAS 1400 is depicted as including a single master unit 1402and three remote antenna units 1404 a-c, any number (including one) ofeach of master unit 1402 and remote antenna units 1404 a-c can be used.Furthermore, a DAS 1400, according to some aspects, can be implementedwithout system controller 1406.

FIG. 22 is a block diagram of a remote antenna unit 1404 configured forperforming RFID detection of passive components. The remote antenna unit1404 can use of RFID tags 1506 a-f to detect the presence of passive RFcomponents. Each passive RF component has an associated RFID tag. Forexample, coaxial cable 1508 or other waveguide is associated with theRFID tag 1506 a. The splitting device 1510 (such as an RF splitter) isassociated with the RFID tag 1506 b. The antennas 1512 a-c arerespectively associated with the RFID tags 1506 c-f. Each of the RFIDtags 1506 a-f can be coupled to a respective passive component via thecoupling circuits 1507 a-f or other suitable coupling circuit or device.

Although four antennas 1512 a-d are depicted, any number of antennas(including one) can be used.

Each of the RFID tags 1506 a-f can include a unique, non-removable, andtamper-proof serial number. Each of the RFID tags 1506 a-f can allow thea respective passive component to be identified by the system controller1406 that is communication with an RFID transceiver 1502 or otherreader/interrogator system in the remote antenna unit 1404. Theinterrogation process can be initiated by the system controller 1406.The system controller 1406 can send a command to the RFID transceiver1502 to begin to probe for RFID tags 1506 a-f.

In some aspects, the RFID transceiver 1502 can transmit the probingsignal via telegram to a coupler 1514. The coupler 1514 can be adirectional coupler (as depicted in FIG. 22) or a non-directionalcoupler. The coupler 1514 can have a coupling ratio of −10 dB or smallerwith respect to the coaxial cable 1508 in direction to the RFID taggedelements. In other aspects, the RFID transceiver 1502 can transmit theprobing signal via a low pass, band pass, or high pass filter can beused.

The probing signal can be communicated via the coaxial cable 1508. Theprobing signal can experience some loss due to the nature of the coaxialcable 1508 or other waveguide. One or more of the RFID tags 1506 a-f canreceive a probing signal that having a signal level above apredetermined threshold for the RFID tag. Non-limiting examples for sucha threshold include signal levels between −15 dBm and −18 dBm. One ormore of the RFID tags 1506 a-f can receive the probing signal via arespective one of coupling circuits 1507 a-f. One or more of the RFIDtags 1506 a-f can generate a responsive signal. The responsive signalcan be communicated to the RFID transceiver 1502 via the coaxial cable1508 or other waveguide.

Although FIG. 22 depicts a remote antenna unit 1404 having four antennas1512 a-c, other implementations are possible. A remote antenna unit 1404can be coupled to any suitable number of antennas. In some aspects, theDAS 1400 may be configured as a low power DAS. A low power DAS mayinclude remote antenna units having fewer antennas. For a DAS using alow RF power, the RFID transceiver 1502 can be included in each remoteantenna unit and/or communicate with each remote antenna unit via acentral system or devices, such as (but not limited to) the master unit1402 and a network coupling the master unit 1402 to each remote antennaunit. Each splitting device 1510, coupler, and antenna of a respectiveremote antenna unit 1404 can be equipped with an RFID tag as depicted inthe FIG. 23. The RFID transceiver 1502 can transmit probing signals andreceive responsive signals from the RFID tags. The implementation andprotocol of the RFID standard can be used to suppress collisions in theresponses from RFID tags. An element discovery can show which elementand associated RFID tag ID is connected to a given remote antenna unit.Periodic probing of the passive components can allow the detection ofchanges in the installation. Periodic probing of the passive componentscan additionally or alternatively be used to identify a faultyconnection or broken cable in the absence of an expected RFID response.

In additional or alternative aspects, the DAS 1400 may be configured asa high power DAS. A high power DAS includes more antennas connected to agiven remote antenna unit 1404 than a low power DAS. More antennas canbe connected to a given remote antenna unit 1404 by increasing theamount of splitting performed by a splitting device 1510. The RFIDsignal link budget can be evaluated to avoid the RFID transceiver 1502signal being reduced to an insufficiently high level by the splitting.An insufficiently high signal can be a signal level that is too low toexcite one or more of the RFID tags 1506 a-f, thereby resulting in noresponsive signal being generated. An RFID implementation having a lowerloss and a higher link budget may be used. Alternatively, multiple RFIDtags 1506 operating on different frequencies can be installed in thepassive components, thereby increasing the flexibility of the signalstrength requirement for signals transmitted by an RFID transceiver1502. For example, an RFID implementation operating at 100-150 kHz maybe used with resonant coupling circuits 1507 a-f that exhibit low passcharacteristics. Other non-limiting examples of RFID implementationinclude RFID implementations operating at 13.56 MHz, 860-915 MHz, andpotentially 2.4 GHz.

FIG. 23 is a block diagram depicting an RFID tag 1506 coupled to apassive component, such as a coaxial cable 1508 or other waveguide, viaa resonant coupling circuit 1507. The RFID tag 1506 can becommunicatively coupled to the coaxial cable 1508 via an attenuation andmatching circuit 1604 and the coupling circuit 1507.

The coupling circuit 1507 can couple an RF signal on the coaxial cable1508 to an RFID tag 1506 via a capacitor 1606 and an inductor 1608. Thecoupling circuit 1507 can have a resonant characteristic provided by thecapacitor 1606 and the inductor 1608. The resonance frequency can be theoperational frequency of the RFID tag 1506. For frequencies separatefrom the resonance frequency, the coupling circuit 1507 can provide ahigh impedance to minimize negative impacts from signals used for mobilecommunication via the DAS 1400. Non-limiting examples of negativeimpacts from signals used for mobile communication can includereflection and loss to other signals on different frequencies.

The attenuation and matching circuit 1604 can include attenuationdevices 1610 a, 1610 b. The RFID tag 1504 can be communicatively coupledto the coupling circuit 1507 via the attenuation device 1610 a. The RFIDtag 1504 can be communicatively coupled to ground via the attenuationdevice 1610 b.

Although the FIG. 23 depicts an attenuation and matching circuit 1604for coupling the RFID tag 1506 to a coupling circuit 1507, otherimplementations are possible. In other aspects, a balun component, suchas (but not limited to) a transformer, can be used in place of theattenuation devices 1610 a, 1610 b.

In additional or alternative aspects, the RFID tag 1506 can be coupledto the coaxial cable 1508 or another passive component via anon-resonant coupling circuit. For example, FIG. 24 is a block diagramof an RFID tag 1506 coupled to a passive component, such as the coaxialcable 1508, via a directional coupler 1702 1702. The directional coupler1702 can be used with a coupling optimized for signals communicated withthe RFID transceiver 1502 and selected for suppressing potentialintermodulation products generated by the RFID tag 1506 in the directionof one or more antennas.

In some aspects, the functionality of the passive component can beindependent of the direction or other orientation of a passive componentas mounted or otherwise installed in a DAS 1400. In other aspects, thefunctionality of the passive component can be dependent on the directionor other orientation of the passive component as mounted or otherwiseinstalled in the DAS 1400. The directional coupler 1702 can allow fordetermining whether a passive component is mounted in the correctdirection. A bias-t element is a non-limiting example of an elementhaving functionality dependent on the direction or other orientation ofthe passive component as mounted or otherwise installed.

In additional or alternative aspects, an RFID tag 508 can becommunicatively coupled to a passive RF component with a radiatingelement, such as an antenna or a leaky feeder. For example, FIG. 25 is ablock diagram of an RFID tag coupled to an antenna 1512 via an aircoupling path. The air coupling path can include a signal path betweenan antenna 1512 and an RFID antenna 1802.

The RFID tag 1506 can be communicatively coupled to the antenna 1512using the RFID antenna 1802. The RFID antenna 1802 can be coupled to theRFID tag 1506 via the coupling circuit 1507. The coupling circuit 1507can be resonant for an operational frequency of the RFID tag 1506. Thecoupling circuit 1507 can block or reduce the signal level of signals atfrequencies other than the operational frequency of the RFID tag 1506.The filtering characteristic of the coupling circuit 1507 can causesignals other than the signal of the RFID transceiver 1502 to besuppressed. Suppressing signals other than the signal of the RFIDtransceiver 1502 can reduce or eliminate potential intermodulationproducts generated by the RFID tag 1506. Decreasing the distance betweenthe RFID antenna 1802 and the antenna 1512 can maintain coupling of at alevel of −20 dB or higher without significantly changing the radiationpattern of the antenna 1512.

In additional or alternative aspects, a given RFID tag can be associatedwith multiple coupling circuits. For example, FIG. 26 is a block diagramof an RFID tag 1506 that is associated with multiple coupling circuits.The coupling circuits include a physical coupling circuit 1507 forcoupling to a coaxial cable 1508 and an RFID antenna 1802 or othersuitable air interface for coupling via air to an antenna 1512 or leakyloss section of a coaxial cable 1508. A power divider 1902 between theRFID tag 1506 and each of the coupling circuit 1507 and the RFID antenna1802 can divide an RFID signal communicated with the RFID transceiversuch that that the RFID signal can be transceived through either or bothof the coupling circuit 1507 and the RFID antenna 1802.

The power divider 1902 depicted in FIG. 26 can allow for determining ofan element associated with an RFID tag with a moveable reader.

Any suitable resonator circuit can be used to implement a resonantcoupling circuit. For example, FIG. 27 is a schematic diagram depictingan example of a series resonator circuit for implementing a resonantcoupling circuit 1507. The series resonator circuit can include aresistor 2002 in series with an inductor 2004 and a capacitor 206. Thecharacteristics of the series resonator circuit allow for suppressingsignals outside of the RFID tag 1506 operating frequency. For example,FIG. 28 is a graph depicting the impedance of the series resonatorcircuit for implementing a resonant coupling circuit 1507. As depictedin FIG. 28, the series resonator circuit can provide high impedancevalues outside of the resonance frequency wr.

In additional or alternative aspects, a multiple pole filter can be usedfor the coupling circuit 1507. Using a multiple pole filter can increasethe suppression of the signals of the wireless standard that aretransported via the coaxial cable.

General Considerations

The present invention has been described with reference to theaccompanying drawings, in which certain aspects of the invention areshown. This invention may, however, be embodied in many different formsand should not be construed as limited to the aspects that are picturedand described herein; rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the invention to those skilled in the art.

Herein, references are made to the “positive” component and the“negative” component of the RFID control signal. Note that since theRFID may be an alternating current signal, in some cases the signal oneach pair may oscillate between being a positive signal and a negativesignal. Consequently, it will be appreciated that references herein to a“positive component” or a “negative component” of an RFID control signalare used to refer to the components of the RFID control signal at agiven point in time in order to conveniently be able to distinguishbetween the two components of the signal.

Unless otherwise defined, all technical and scientific terms that areused in this disclosure have the same meaning as commonly understood byone of ordinary skill in the art to which this invention belongs. Theterminology used in the above description is for describing particularaspects only and is not intended to be limiting of the invention. Asused in this disclosure, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will also be understood that when an element(e.g., a device, circuit, etc.) is referred to as being “connected” or“coupled” to another element, it can be directly connected or coupled tothe other element or intervening elements may be present. In contrast,when an element is referred to as being “directly connected” or“directly coupled” to another element, there are no intervening elementspresent.

Certain aspects of the present invention have been described above withreference to flowchart illustrations. It will be understood that someblocks of the flowchart illustrations may be combined or split intomultiple blocks, and that the blocks in the flow chart diagrams need notnecessarily be performed in the order illustrated in the flow charts.

In the drawings and specification, there have been disclosed typicalaspects of the invention and, although specific terms are employed, theyare used in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention being set forth in the followingclaims.

What is claimed is:
 1. A system, comprising: a coupling circuit betweena communications network and an RFID tag associated with a passiveelement of a distributed antenna system, the coupling circuit beingconfigured for allowing an RFID signal received from an RFID transmitterover the communications network to be transported to the RFID tag andfor substantially preventing mobile communication signals on thecommunications network from being transported to the RFID tag.
 2. Thesystem of claim 1, further comprising: the RFID transmitter in a fixedlocation in the distributed antenna system, the fixed location beingremote to the passive element; and the passive element, the passiveelement being a non-powered element.
 3. The system of claim 1, whereinthe communications network comprises a coaxial cable.
 4. The system ofclaim 1, wherein the coupling circuit comprises a physical couplingbetween the RFID tag and the communications network.
 5. The system ofclaim 4, wherein the physical coupling comprises a resonant couplingcircuit, the resonant coupling circuit configured with a resonantfrequency allowing the RFID signal received from the RFID transmitterover the communications network to be transported to the RFID tag andfor substantially preventing the mobile communication signals on thecommunications network from being transported to the RFID tag.
 6. Thesystem of claim 4, wherein the physical coupling comprises at least oneof a directional coupler or a non-directional coupler.
 7. The system ofclaim 1, wherein the coupling circuit comprises an air coupling betweenthe RFID tag and the communications network.
 8. The system of claim 7,wherein the air coupling comprises an RFID antenna communicativelycoupled to the RFID tag and configured to receive the RFID signal froman antenna of the distributed antenna system.
 9. The system of claim 1,wherein the coupling circuit comprises: a physical coupling between theRFID tag and the communications network; and an air coupling between theRFID tag and the communications network.
 10. The system of claim 9,wherein the coupling circuit further comprises a power divider betweenthe RFID tag and each of the physical coupling and the air coupling. 11.A distributed antenna system comprising: a communications network; aRFID transmitter positioned in a remote antenna unit; an RFID tagassociated with a passive element remote from a position of the RFIDtransmitter over the communications network; a coupling circuitconfigured for providing a physical coupling between the RFID tag andthe communications network.
 12. The distributed antenna system of claim11, wherein the coupling circuit is configured to allow RFID signalsthrough the coupling circuit and substantially prevent non-RFID signalsfrom passing through the coupling circuit.
 13. The distributed antennasystem of claim 11, wherein the communications network comprises acoaxial cable.
 14. The distributed antenna system of claim 11, whereinthe coupling circuit comprises a resonant coupling circuit, the resonantcoupling circuit configured with a resonant frequency allowing an RFIDsignal received from the RFID transmitter over the communicationsnetwork to be transported to the RFID tag and for substantiallypreventing mobile communication signals on the communications networkfrom being transported to the RFID tag.
 15. The distributed antennasystem of claim 11, further comprising an air coupling between the RFIDtag and the communications network.
 16. The distributed antenna systemof claim 15, wherein the air coupling comprises an RFID antennacommunicatively coupled to the RFID tag and configured to receive anRFID signal from an antenna of the distributed antenna system, the RFIDsignal transmitted by the RFID transmitter.
 17. A method comprising:providing a coupling circuit between a communications network and anRFID tag associated with a passive element of a distributed antennasystem; and transmitting an RFID signal received from an RFIDtransmitter to the RFID tag via the communications network and thecoupling circuit, wherein the coupling circuit substantially preventsmobile communication signals on the communications network from beingcommunicated to the RFID tag.
 18. The method of claim 17, furthercomprising: providing the RFID transmitter in a fixed location in thedistributed antenna system, wherein the fixed location is remote to thepassive element.
 19. The method of claim 17, wherein the communicationsnetwork comprises a coaxial cable.
 20. The method of claim 17, whereinproviding the coupling circuit comprises a providing a resonant couplingcircuit allowing the RFID signal received from the RFID transmitter overthe communications network to be transported to the RFID tag and forsubstantially preventing the mobile communication signals on thecommunications network from being transported to the RFID tag.
 21. Themethod of claim 17, wherein the coupling circuit comprises an aircoupling between the RFID tag and the communications network.
 22. Themethod of claim 21, wherein providing the coupling circuit that includesthe air coupling comprises providing an RFID antenna communicativelycoupled to the RFID tag; and further comprising receiving the RFIDsignal from an antenna of the distributed antenna system.